Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Nate Duehr]

Cort Buffington wrote:

> And for the rest of the list, i can take this conversation with Jeff 
> off-line if we're putting out a bad S/N ratio (pun intended)

I'm enjoying reading along.  How else do we all learn and come up with 
interesting new ideas?

:-)

Nate WY0X

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Nate Duehr]

Jeff DePolo wrote:
>  
>> Or, bring all the remote receivers in on digital links, and 
>> encode a bitstream carrying continuous quieting level data?
> 
> Sounds like a modernization of the old TAC system that used in-band tone
> signalling to indicate quieting levels.  The quieting level was represented
> by two tones, A, and B, with A-only, A and B, or B-only representing 10, 20,
> and 30 dB quieting respectively IIRC.

What would be FAR more interesting (but hard to build) would be a 
"digital voter" for the fully-digital systems like P25, D-STAR, etc.

The digital signal is received at mutltiple sites, sent digitally to the 
voter, which does the math (very fast) by looking at the streams, 
including the forward-error-correction (FEC) bits and seeing which 
receiver is REALLY receiving the cleanest signal, and sends that on to 
the transmitter.

Do that with as little buffering as possible (some is inevitable) and 
your voting would feel "continuous" on a fully-digital system like P25, 
D-STAR, etc... any system where the user radio does the A/D conversion.

You also need a master clock source you trust to "align" all the stuff 
that's flying toward the voter.

There's already a working prototype of a "D-STAR extender" that receives 
a D-STAR signal from a standard FM discriminator and decodes it in PC 
software, and forwards it to a D-STAR Gateway for re-transmission, but 
that requires a separate receive frequency for the "extender" other than 
the repeater's input frequency.  Not spectrally efficient.

But it's a "start" on better things.

It *could* even be put on the input frequency and different callsign 
routes used to "select" a receiver if the Icom implementation of D-STAR 
didn't have their repeaters willing to repeat even if they missed the 
routing information (i.e. noisy signal to the main receiver site).

Nate WY0X

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[wd8chl]

[EMAIL PROTECTED] wrote:
> At 6/20/2008 15:52, you wrote:
> 
>> I'm not sure I follow. I would think that for peak and valley detection to
>> work right, you need to look at the voice spectrum, not the noise spectrum,
>> and use the ratio of the peaks to valleys to compute a value indicitive of
>> the S/N, and then compare S/N values among the active channels to determine
>> which gets voted. I think that this kind of peak to valley ratioed
>> comparison would help "even out" differences in audio levels between
>> receivers (since you're comparing ratios, not absolute levels). I would
>> also think that by looking at the audio passband alone, it would also
>> minimize the detrimental effect of frequency response differences between
>> sources, particulary with regard to the typical high-end rolloff above the
>> audio passband for sources backhauled across links as compared to the local
>> receiver, which is often the most challenging obstacle to overcome as
>> mentioned previously.
> 
> Has anyone actually designed a voter than works on this principle?  One 
> issue I see is that proper operation of the voter may depend on "proper" 
> user input signals.  A user radio with a hot mic in a noisy environment 
> (hence constant deviation) would not be properly voted, particularly if the 
> user wasn't moving.  Several examples of such a scenario occurring during 
> the LA Marathon come to mind...
> 
> Bob NO6B


The GE voters work this way-and have since the Mastr Pro days.

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Cort Buffington]

bandpass filter --> envelope detector (integrator) --> ADC

The integrator would need to be able to integrate the lowest frequency  
allowed by the bandpass. So if I bandpass at 2-3kHz (2nd order) then  
I'll probably need to build the integrator to work down to 1kHz. The  
integrator also chops off the lower 1/2 of the AC waveform. So now I  
have a (quickly) varying DC voltage associated with the slope of the  
curve of the audio signal.


The analog way to do this is feed outputs of each of these circuits  
into sample and hold circuits looking for the LOWEST value. There  
would be some trickery associated with resetting the holds  
periodically, etc, but the basic idea is the lowest value is the  
receiver with the least amount of noise.


I would feed the output of the analog circuit directly into the ADC of  
the microprocessor and work with varying techniques in software. Some  
of those would include calibration of the voter by supplying signals  
at various quieting levels and using them as setpoints. For example,  
if a fully quieted signal on the local receiver produces (wild guesses  
start here) .7VDC, that could be set at the "fully quiet" level for  
that receiver. If the remotes fully quiet at 1.1VDC because of the  
difference with radio links, then that could be set as the fully quiet  
level. In all of the analog S/N detectors I've built, I had the one  
problem you pointed out -- the local receiver is the odd duck.


The thing I like the most about this is that if the idea for the  
bandpass/integrator is sound, then minor programming tweaks will be  
where the detailed work is. Right now my work is focussed on making a  
good analog circuit that I like well enough to head into software work  
without coming back for a complete re-design :)


On Jun 21, 2008, at 10:37 AM, Jeff DePolo wrote:



> Here's where I'm probably making a mistake: The "energy" in
> the audio spectrum is the intelligence (signal) energy +
> noise energy at any time t. Am I missing something where the
> intelligence energy is reduced on a noisy signal or something?

Depending on how you look at it, yes, because you have limited dynamic
range. In two-way, we have limiters/clippers to prevent  
overmodulation. A
peak detector should, theoretically, produce the same output voltage  
whether
it's fed a fully-deviated 1 kHz tone, or whether it's fed white  
noise with

the same peak amplitude as the tone.

Give me a better idea of what you envision for a detector.

--- Jeff




--
Cort Buffington
H: +1-785-838-3034
M: +1-785-865-7206

RE: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Jeff DePolo]

> Here's where I'm probably making a mistake: The "energy" in 
> the audio spectrum is the intelligence (signal) energy + 
> noise energy at any time t. Am I missing something where the 
> intelligence energy is reduced on a noisy signal or something?

Depending on how you look at it, yes, because you have limited dynamic
range.  In two-way, we have limiters/clippers to prevent overmodulation.  A
peak detector should, theoretically, produce the same output voltage whether
it's fed a fully-deviated 1 kHz tone, or whether it's fed white noise with
the same peak amplitude as the tone.

Give me a better idea of what you envision for a detector.

--- Jeff

RE: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[no6b]

At 6/20/2008 15:52, you wrote:

>I'm not sure I follow. I would think that for peak and valley detection to
>work right, you need to look at the voice spectrum, not the noise spectrum,
>and use the ratio of the peaks to valleys to compute a value indicitive of
>the S/N, and then compare S/N values among the active channels to determine
>which gets voted. I think that this kind of peak to valley ratioed
>comparison would help "even out" differences in audio levels between
>receivers (since you're comparing ratios, not absolute levels). I would
>also think that by looking at the audio passband alone, it would also
>minimize the detrimental effect of frequency response differences between
>sources, particulary with regard to the typical high-end rolloff above the
>audio passband for sources backhauled across links as compared to the local
>receiver, which is often the most challenging obstacle to overcome as
>mentioned previously.

Has anyone actually designed a voter than works on this principle?  One 
issue I see is that proper operation of the voter may depend on "proper" 
user input signals.  A user radio with a hot mic in a noisy environment 
(hence constant deviation) would not be properly voted, particularly if the 
user wasn't moving.  Several examples of such a scenario occurring during 
the LA Marathon come to mind...

Bob NO6B

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Cort Buffington]

I don't think I'm really looking at something a lot different --  
probably I need to do some more building and measuring and analyzing.


I was thinking that 2kHz to 3kHz would contain both a good amount of  
noise, be below the pass-band cut-off , and have enough voice  
components in it That was a wild guess based on the Spetra-TAC  
voter working above 2kHz with the theory of operation section  
describing, essentially, a fair amount of noise and mostly vocal  
harmonics with less energy, though it still looks for valleys.


My thinking on the peak-valley thing worked like this and I'M probably  
the one not thinking clearly: I know voice isn't a "tone" but I'll use  
the tone concept for simplicity -- I'm essentially freezing a couple  
of moments in time, so that's cool? If I have that ubiquitous 1kHz  
audio signal modulated at +/- 3kHz fed to two receivers, and dead  
carrier -- my two "test cases" if you will. If one receiver is  
considerably more quieted than the other then:


When there is dead air, the valley would be detected. The noisy  
receiver would show a "higher" level -- more energy in the audio  
spectrum than the less noisy. Low level is best signal.


When the 1kHz +/-3kHz audio signal is present, the noisy receiver  
would show a "higher" level -- more energy in the audio spectrum due  
to the signal + noise component. Lower level is the best signal.


Here's where I'm probably making a mistake: The "energy" in the audio  
spectrum is the intelligence (signal) energy + noise energy at any  
time t. Am I missing something where the intelligence energy is  
reduced on a noisy signal or something?


Seriously, I am doing building and measuring, but don't have the  
experience of the group, and also may not be using some terms correctly.


On Jun 20, 2008, at 5:52 PM, Jeff DePolo wrote:


> Not quite enough of a programmer to take on the DSP, but will
> likely look at the peaks and valleys with the ADC. I'm not
> sure why I'd need more than one noise circuit though. I don't
> want to do a sample and hold, the ADC and software can do
> that. I was thinking build one analog circuit and look for
> valleys and peaks when the ADC reads the analog circuit
> output -- that is to say, keep track of the highest level and
> lowest level over a certain very short time period

I'm not sure I follow. I would think that for peak and valley  
detection to
work right, you need to look at the voice spectrum, not the noise  
spectrum,
and use the ratio of the peaks to valleys to compute a value  
indicitive of
the S/N, and then compare S/N values among the active channels to  
determine

which gets voted. I think that this kind of peak to valley ratioed
comparison would help "even out" differences in audio levels between
receivers (since you're comparing ratios, not absolute levels). I  
would

also think that by looking at the audio passband alone, it would also
minimize the detrimental effect of frequency response differences  
between
sources, particulary with regard to the typical high-end rolloff  
above the
audio passband for sources backhauled across links as compared to  
the local

receiver, which is often the most challenging obstacle to overcome as
mentioned previously.

If you look at only the noise spectrum, then peaks and valleys don't  
have
much relevance; you would only be able to compare the average noise  
levels
to determine which channel gets voted. This is way the LDG is  
designed. If
you look at the noise spectrum only, audio that is full-quieting  
would have
a peak to valley ratio approaching unity, but so would a hissy, but  
stable,
signal. But if you looked at the voice spectrum, the full-quieting  
signal
would have a greater ratio between peaks and valleys than would one  
with a

steady hiss behind the audio.

Maybe you're suggesting something completely different and it went  
over my

head?

--- Jeff





--
Cort Buffington
H: +1-785-838-3034
M: +1-785-865-7206

RE: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[n9wys]

No, actually I'm enjoying the discussion!  (But I'm only one subscriber on
the list.)

 

Mark - N9WYS

 

From: Repeater-Builder@yahoogroups.com On Behalf Of Cort Buffington



  --(snip)--

And for the rest of the list, i can take this conversation with Jeff
off-line if we're putting out a bad S/N ratio (pun intended)

 

73 DE N0MJS

RE: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Jeff DePolo]

> Not quite enough of a programmer to take on the DSP, but will 
> likely look at the peaks and valleys with the ADC. I'm not 
> sure why I'd need more than one noise circuit though. I don't 
> want to do a sample and hold, the ADC and software can do 
> that. I was thinking build one analog circuit and look for 
> valleys and peaks when the ADC reads the analog circuit 
> output -- that is to say, keep track of the highest level and 
> lowest level over a certain very short time period 

I'm not sure I follow.  I would think that for peak and valley detection to
work right, you need to look at the voice spectrum, not the noise spectrum,
and use the ratio of the peaks to valleys to compute a value indicitive of
the S/N, and then compare S/N values among the active channels to determine
which gets voted.  I think that this kind of peak to valley ratioed
comparison would help "even out" differences in audio levels between
receivers (since you're comparing ratios, not absolute levels).  I would
also think that by looking at the audio passband alone, it would also
minimize the detrimental effect of frequency response differences between
sources, particulary with regard to the typical high-end rolloff above the
audio passband for sources backhauled across links as compared to the local
receiver, which is often the most challenging obstacle to overcome as
mentioned previously.

If you look at only the noise spectrum, then peaks and valleys don't have
much relevance; you would only be able to compare the average noise levels
to determine which channel gets voted.  This is way the LDG is designed.  If
you look at the noise spectrum only, audio that is full-quieting would have
a peak to valley ratio approaching unity, but so would a hissy, but stable,
signal.  But if you looked at the voice spectrum, the full-quieting signal
would have a greater ratio between peaks and valleys than would one with a
steady hiss behind the audio.

Maybe you're suggesting something completely different and it went over my
head?

--- Jeff

RE: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Jeff DePolo]

 
> Or, bring all the remote receivers in on digital links, and 
> encode a bitstream carrying continuous quieting level data?

Sounds like a modernization of the old TAC system that used in-band tone
signalling to indicate quieting levels.  The quieting level was represented
by two tones, A, and B, with A-only, A and B, or B-only representing 10, 20,
and 30 dB quieting respectively IIRC.

Still, you need some way of quantifying the noise at the remote receiver,
and encoding that data, and sending it downstream.  And likewise something
to select among the audio sources at the central site based on that data.
It's still basically a S/N voting system, only the circuitry isn't all
concentrated at the central site, it's distributed.  

If you had digital links with wide AF response (like to 6 kHz), then there
wouldn't be any real advantage to measuring noise at the far end.  But if
the digital links were Nyquist-limited to less, like a "voice grade" 8
kHz-sampled circuit typically is, then having the S/N quantified at the far
end could definately be advantageous.

I have some surplus broadcast STL equipment that I've wanting to use for
multiplexed links (Moseley DSP6000 for those that are familiar).  These will
put four 7.5 kHz audio bandwidth channels on one 256 kb/s pipe.  The
resulting data stream comes out the spigot on the back as CPFSK compatible
with wideband FM equipment.  With AF response out to 7.5 kHz, and gobs more
dynamic range and S/N than necessary for two-way, they'd be the bee's knees
for backhauling multiple receivers.

--- Jeff Wn3A

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Cort Buffington]

Yes, that would be the one I'd prefer -- if I were to go that "Far"  
with it, I think using digital links with signal strength data thrown  
it would be WAY cool.


On Jun 20, 2008, at 2:30 PM, Paul Plack wrote:



Or, bring all the remote receivers in on digital links, and encode a  
bitstream carrying continuous quieting level data?


- Original Message -
From: Jeff DePolo
To: Repeater-Builder@yahoogroups.com
Sent: Friday, June 20, 2008 1:11 PM
Subject: RE: [Repeater-Builder] Re: Anyone familiar with the LDG  
RVS-8 Voting system?



> My exact issue when looking at S/N generators -- the analog
> part. Which is why I am about to build a 2-3kHz bandpass
> filter and switch to looking for low averaged values by less
> integration (shorter delta t) and faster sampling in the ADC
> to look for "valleys" in a "better" way. Make any sense at all?

Yes, but you will have more immunity to audio level variations between
receivers if you do peak-and-valley comparison. Compare the ratio of  
peaks

to valleys rather than valley-only and you'll get a more accurate
measurement of short-term S/N. Yes, you'll have two sets of  
detectors for
each channel (one for peaks, one for valleys), and yes, you'll have  
twice as

many inputs to mux into the ADC, but I think you'd end up with a
superior-performing product. Something to think about or tinker with.

Of course, you could avoid all of the analog nonsense and do it with  
DSP,

that would be a cool project. Wish I had more time for these kinds of
projects...

--- Jeff WN3A






--
Cort Buffington
H: +1-785-838-3034
M: +1-785-865-7206

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Cort Buffington]

Not quite enough of a programmer to take on the DSP, but will likely  
look at the peaks and valleys with the ADC. I'm not sure why I'd need  
more than one noise circuit though. I don't want to do a sample and  
hold, the ADC and software can do that. I was thinking build one  
analog circuit and look for valleys and peaks when the ADC reads the  
analog circuit output -- that is to say, keep track of the highest  
level and lowest level over a certain very short time period The  
highest high and highest low will indicate more noise component? Yes?  
Am I missing the boat?


And for the rest of the list, i can take this conversation with Jeff  
off-line if we're putting out a bad S/N ratio (pun intended)


73 DE N0MJS

On Jun 20, 2008, at 2:11 PM, Jeff DePolo wrote:



> My exact issue when looking at S/N generators -- the analog
> part. Which is why I am about to build a 2-3kHz bandpass
> filter and switch to looking for low averaged values by less
> integration (shorter delta t) and faster sampling in the ADC
> to look for "valleys" in a "better" way. Make any sense at all?

Yes, but you will have more immunity to audio level variations between
receivers if you do peak-and-valley comparison. Compare the ratio of  
peaks

to valleys rather than valley-only and you'll get a more accurate
measurement of short-term S/N. Yes, you'll have two sets of  
detectors for
each channel (one for peaks, one for valleys), and yes, you'll have  
twice as

many inputs to mux into the ADC, but I think you'd end up with a
superior-performing product. Something to think about or tinker with.

Of course, you could avoid all of the analog nonsense and do it with  
DSP,

that would be a cool project. Wish I had more time for these kinds of
projects...

--- Jeff WN3A





--
Cort Buffington
H: +1-785-838-3034
M: +1-785-865-7206

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Paul Plack]

Or, bring all the remote receivers in on digital links, and encode a bitstream 
carrying continuous quieting level data?

  - Original Message - 
  From: Jeff DePolo 
  To: Repeater-Builder@yahoogroups.com 
  Sent: Friday, June 20, 2008 1:11 PM
  Subject: RE: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting 
system?



  > My exact issue when looking at S/N generators -- the analog 
  > part. Which is why I am about to build a 2-3kHz bandpass 
  > filter and switch to looking for low averaged values by less 
  > integration (shorter delta t) and faster sampling in the ADC 
  > to look for "valleys" in a "better" way. Make any sense at all?

  Yes, but you will have more immunity to audio level variations between
  receivers if you do peak-and-valley comparison. Compare the ratio of peaks
  to valleys rather than valley-only and you'll get a more accurate
  measurement of short-term S/N. Yes, you'll have two sets of detectors for
  each channel (one for peaks, one for valleys), and yes, you'll have twice as
  many inputs to mux into the ADC, but I think you'd end up with a
  superior-performing product. Something to think about or tinker with. 

  Of course, you could avoid all of the analog nonsense and do it with DSP,
  that would be a cool project. Wish I had more time for these kinds of
  projects...

  --- Jeff WN3A



   

RE: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Jeff DePolo]

> My exact issue when looking at S/N generators -- the analog 
> part. Which is why I am about to build a 2-3kHz bandpass 
> filter and switch to looking for low averaged values by less 
> integration (shorter delta t) and faster sampling in the ADC 
> to look for "valleys" in a "better" way. Make any sense at all?

Yes, but you will have more immunity to audio level variations between
receivers if you do peak-and-valley comparison.  Compare the ratio of peaks
to valleys rather than valley-only and you'll get a more accurate
measurement of short-term S/N.  Yes, you'll have two sets of detectors for
each channel (one for peaks, one for valleys), and yes, you'll have twice as
many inputs to mux into the ADC, but I think you'd end up with a
superior-performing product.  Something to think about or tinker with.  

Of course, you could avoid all of the analog nonsense and do it with DSP,
that would be a cool project.  Wish I had more time for these kinds of
projects...

--- Jeff WN3A

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Cort Buffington]

My exact issue when looking at S/N generators -- the analog part.  
Which is why I am about to build a 2-3kHz bandpass filter and switch  
to looking for low averaged values by less integration (shorter delta  
t) and faster sampling in the ADC to look for "valleys" in a "better"  
way. Make any sense at all?


On Jun 20, 2008, at 10:23 AM, Jeff DePolo wrote:



> You mentioned a re-write of the LDG software. Would you be
> willing to share whether or not you changed what the
> processor is looking at from the ADC to consider a channel to
> be the best? What intrigues me most about the LDG is that the
> difference between being a straight S/N voter and a "valley"
> voter is only software or some mix, or both, etc.

No, the software still uses the same DC sample from the noise
filter/integrator in the same way. However, it does make significant
improvements in what is done with the A/D values via math, much of  
which

involves user-adjustable parameters.

The problem many people run into when trying to balance a voted  
system is
that the local receiver is always the odd duck because it will  
present more

high-frequency noise than will receivers that use RF links back to the
voting comparator. Improving the noise filter in the voter such that  
it
looks at a narrower spectra for noise helps that problem (i.e.  
instead of
just a high-pass filter, bandpass). The most effective outboard fix  
is to
simply EQ the local receiver so that its high frequency response  
closely
mimics that of the other receivers audio is passing through the RF  
link

where additional HF attenuation is incurred.

--- Jeff




--
Cort Buffington
H: +1-785-838-3034
M: +1-785-865-7206

RE: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Jeff DePolo]

> Many Burger Kings have a full-duplex cross band radio/repeater 
> system in the drive through operation. No voters but there is 
> an included sensor input to detect cars at the order take window.
> 
> cheers, 
> s. 

And don't try to tell me that you haven't, at the very least, _thought_
about messing with the order-takers...

If memory serves, 154.570 (a MURS channel) was the freq used from the
customer to the window.

Here's something for you Skipp, down the road from you a bit.  I got a
chuckle out of it - 121 kilometers of service area for Jack in the Box and
Taco Bell drive-throughs?  Frequency coordination at its finest.

http://fjallfoss.fcc.gov/edocs_public/attachmatch/DA-07-3072A1.pdf

--- Jeff

RE: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Jeff DePolo]

 
> You mentioned a re-write of the LDG software. Would you be 
> willing to share whether or not you changed what the 
> processor is looking at from the ADC to consider a channel to 
> be the best? What intrigues me most about the LDG is that the 
> difference between being a straight S/N voter and a "valley" 
> voter is only software or some mix, or both, etc.

No, the software still uses the same DC sample from the noise
filter/integrator in the same way.  However, it does make significant
improvements in what is done with the A/D values via math, much of which
involves user-adjustable parameters.

The problem many people run into when trying to balance a voted system is
that the local receiver is always the odd duck because it will present more
high-frequency noise than will receivers that use RF links back to the
voting comparator.  Improving the noise filter in the voter such that it
looks at a narrower spectra for noise helps that problem (i.e. instead of
just a high-pass filter, bandpass).  The most effective outboard fix is to
simply EQ the local receiver so that its high frequency response closely
mimics that of the other receivers audio is passing through the RF link
where additional HF attenuation is incurred.

--- Jeff

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Cort Buffington]

Jeff,

You mentioned a re-write of the LDG software. Would you be willing to  
share whether or not you changed what the processor is looking at from  
the ADC to consider a channel to be the best? What intrigues me most  
about the LDG is that the difference between being a straight S/N  
voter and a "valley" voter is only software or some mix, or both,  
etc.


73 DE N0MJS

On Jun 19, 2008, at 9:31 PM, Jeff DePolo wrote:



> I'm curious. Why do you use the LDG over the surplus
> commercial stuff?

I started with one single-site 440 repeater. Then I decided to add a  
remote
receiver. At first the two receivers were PL-steered, but that was a  
PITA

for users, so I decided it was time for a voter (or more technically
correct, a voting comparator). So I got my hands on a GE voter, which
worked OK, but I figured "there must be something better out there  
by now"
as the GE was probably 20 years old already at that point. I  
switched to a
Doug Hall, but I was more than a little unhappy with its performance  
(sorry
Doug if you're listening), though I learned later that they made  
substantial
improvements over the early ones like I had, so don't take what I  
wrote as
"don't buy a DH voter". I had already gotten rid of the GE, so I  
stuck with
the DH for a couple of years during which time I added a second  
repeater to
the system, and then a third. At that point I was out of channels on  
my
4-port DH card. So I tinkered with a SpectraTAC on the bench a bit,  
but
never put it on the air. I didn't really need more voted channels,  
four was

enough, I just needed more "inputs" to handle the additional linked
repeaters I was building. So, instead, I designed/built an 8-channel
prioritizer (more about that later) to deal with additional linked  
repeaters
as they came online, and left the four-channel DH to handle the  
receiver for

the main repeater and its satellites.

Then the LDG came out, so I bought one to play with. It was just a  
kit back
then, no cabinet was available. I liked the ability to adjust noise  
levels
independently. I liked having a modern front-panel user interface.  
While
there were (and still are) some things I don't like about it, it did  
the
job. So I bought several more over the years. They've all been  
modified to
improve the response of the noise filter to reduce voice influence.  
They've
all had the PTT relay removed. They've all been loaded with custom  
software
(no, I'm not going to say where it came from, but I will say that it  
was a
total re-write). After all that I've settled into a point of being  
"mostly

happy" with them.

Aside from the voters, I have prioritizers at a number of sites.  
These are
boards I designed and built myself. Most are 4-ports, some are 8- 
ports. I
have some sites where I really don't need voting per se, but rather  
I need
the ability to "concentrate" multiple receivers into one outbound  
link, and

that's where the prioritizers come in. Think of the prioritizer as an
8-input (or 4-input) 1-output audio switch.

In the case of my main site, I have 12 links coming in, five of  
which are
remote receivers for the repeater located there, the remaining 7 are  
links

coming in from other sites. I have one 8-channel LDG voter and one
8-channel prioritizer. The voter takes in the links from the five  
remote
receivers plus the local receiver. The output of the voter feeds  
channel 1
(highest priority) on the prioritizer. The seven inbound links from  
the
other sites go to channels 2 through 8 on the prioritizer. The  
output of
the prioritizer goes to the controller. Sound confusing? It's not.  
Draw a

block diagram of what I wrote and it should look pretty simple.

At other sites, I may have a local repeater, plus several inbound  
links from
outlying repeaters in the network. Or it may be a link relay site  
that has
no local repeater. Whatever the case, all of the receivers funnel  
into a
prioritizer, which then shoots a single outbound link to the next  
repeater
down the line en route to the main site. The network is a big star,  
with
everything being managed and controlled from the main site. No audio  
is

repeated locally at any outlying repeater; the audio from all of the
receivers end up being funneled into the main site through a network  
of RF

links, voters, and prioritizers.

Although I have some sites that need some serious TLC (I just don't  
have
time for ham radio these days), when everything is/was working 100%  
there

are around 55 receivers (combination of repeater receivers, satellite
receivers, and link receivers) that connect to voters and/or  
prioritizers,
and, when everything's working right, you can't tell the difference  
in the
audio from a receiver at the main site from a receiver that's six  
hops away.


> I think -- THINK -- you're the "Voter King" here in the currently  
active
> folks on the list... more voting than anyone else? What do you  
think?


No, I'm Burger King, not Voter King. I 

RE: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Jeff DePolo]

 
> I'm curious. Why do you use the LDG over the surplus 
> commercial stuff? 

I started with one single-site 440 repeater.  Then I decided to add a remote
receiver.  At first the two receivers were PL-steered, but that was a PITA
for users, so I decided it was time for a voter (or more technically
correct, a voting comparator).   So I got my hands on a GE voter, which
worked OK, but I figured "there must be something better out there by now"
as the GE was probably 20 years old already at that point.   I switched to a
Doug Hall, but I was more than a little unhappy with its performance (sorry
Doug if you're listening), though I learned later that they made substantial
improvements over the early ones like I had, so don't take what I wrote as
"don't buy a DH voter".  I had already gotten rid of the GE, so I stuck with
the DH for a couple of years during which time I added a second repeater to
the system, and then a third.  At that point I was out of channels on my
4-port DH card.  So I tinkered with a SpectraTAC on the bench a bit, but
never put it on the air.  I didn't really need more voted channels, four was
enough, I just needed more "inputs" to handle the additional linked
repeaters I was building.  So, instead, I designed/built an 8-channel
prioritizer (more about that later) to deal with additional linked repeaters
as they came online, and left the four-channel DH to handle the receiver for
the main repeater and its satellites.

Then the LDG came out, so I bought one to play with.  It was just a kit back
then, no cabinet was available.  I liked the ability to adjust noise levels
independently.  I liked having a modern front-panel user interface.  While
there were (and still are) some things I don't like about it, it did the
job.  So I bought several more over the years.  They've all been modified to
improve the response of the noise filter to reduce voice influence.  They've
all had the PTT relay removed.  They've all been loaded with custom software
(no, I'm not going to say where it came from, but I will say that it was a
total re-write).  After all that I've settled into a point of being "mostly
happy" with them.

Aside from the voters, I have prioritizers at a number of sites.  These are
boards I designed and built myself.  Most are 4-ports, some are 8-ports.  I
have some sites where I really don't need voting per se, but rather I need
the ability to "concentrate" multiple receivers into one outbound link, and
that's where the prioritizers come in.  Think of the prioritizer as an
8-input (or 4-input) 1-output audio switch.  

In the case of my main site, I have 12 links coming in, five of which are
remote receivers for the repeater located there, the remaining 7 are links
coming in from other sites.  I have one 8-channel LDG voter and one
8-channel prioritizer.  The voter takes in the links from the five remote
receivers plus the local receiver.  The output of the voter feeds channel 1
(highest priority) on the prioritizer.  The seven inbound links from the
other sites go to channels 2 through 8 on the prioritizer.  The output of
the prioritizer goes to the controller.  Sound confusing?  It's not.  Draw a
block diagram of what I wrote and it should look pretty simple.

At other sites, I may have a local repeater, plus several inbound links from
outlying repeaters in the network.  Or it may be a link relay site that has
no local repeater.  Whatever the case, all of the receivers funnel into a
prioritizer, which then shoots a single outbound link to the next repeater
down the line en route to the main site.  The network is a big star, with
everything being managed and controlled from the main site.  No audio is
repeated locally at any outlying repeater; the audio from all of the
receivers end up being funneled into the main site through a network of RF
links, voters, and prioritizers.

Although I have some sites that need some serious TLC (I just don't have
time for ham radio these days), when everything is/was working 100% there
are around 55 receivers (combination of repeater receivers, satellite
receivers, and link receivers) that connect to voters and/or prioritizers,
and, when everything's working right, you can't tell the difference in the
audio from a receiver at the main site from a receiver that's six hops away.

> I think -- THINK -- you're the "Voter King" here in the currently active 
> folks on the list... more voting than anyone else? What do you think? 

No, I'm Burger King, not Voter King.  I age my crystals in the french fryer,
I only climb towers while wearing a cardboard crown, and I stuff my duplexer
cavities with two all beef patties, special sauce, lettuce, cheese, pickles,
onions and a sesamee seed bun.  Thank you, drive through.

--- Jeff

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Nate Duehr]

Jeff DePolo wrote:
> end.  All of my LDG's have add-on front ends that do this, among other
> things (such as providing logic to switch between COR AND PL versus COR
> only).

Jeff, if there's one person on this list I'd trust for voting/voter 
knowledge, it's you...

I'm curious.  Why do you use the LDG over the surplus commercial stuff? 
  Or do you have "all of the above"?  Any particular thoughts (not 
trying to start a flame-fest, but you have MASSIVELY voted systems, so 
your opinion having "been there, done that, a LOT!" counts heavily, for 
sure!) on what and why you do your systems the way you have them?

I think -- THINK -- you're the "Voter King" here in the currently active 
folks on the list... more voting than anyone else?  What do you think? 
Is it true?  :-)

Nate WY0X

RE: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Jeff DePolo]

> Note that the LDG voter does NOT use TTL voltages on the COR 
> inputs !
> This bit me HARD a few years ago.

They're "raw" CMOS inputs, with those chips running directly off the 12V (or
13.8 or whatever) supply, i.e. no internal voltage regulation.  The high/low
transition points for the input device (CD4053) will vary depending on the
supply voltage.  This burned me once too.  I was powering the LDG off a
Micor ferro (along with the rest of the Micor station).  When the station
was un-keyed, the DC supply would rise up to around 15V (typical of those
supplies, and perfectly harmless).  That moved the transition voltages up.
When the station was keyed, the supply voltage sagged to about 12.8V, moving
the transition points down.  Guess what?  My high-going COR into the LDG was
caught in that "twilight zone" between the high transition voltage points,
so the COR would only be recognized if the receiver went active while the
repeater was keyed (i.e. when the supply voltage was low).  If the repeater
was not keyed, you were effectively locked out of the repeater - you had to
wait for it to ID in order to be able to get in, and then you had to make
sure you never let the carrier drop!

Bad design IMHO.  I prefer to have something more hearty, and un-affected by
supply voltages.  Something like a ULN2804 darlington array with 5V input
pull-ups that the user can enable or disable makes a nice flexible front
end.  All of my LDG's have add-on front ends that do this, among other
things (such as providing logic to switch between COR AND PL versus COR
only).
 
--- Jeff WN3A

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[wd8chl]

Mike Morris WA6ILQ wrote:
> At 09:06 AM 06/17/08, you wrote:
>>> I am building a large repeater system here in SE Kansas for SkyWarn
>>> and I am wanting to use the RVS-8 Voter.
>>>
>>> Our system uses Motorola Maxtracs for pretty much every aspect
>>> of our giant 15 county coverage repeater.
>>>
>>> Has anyone successfully used Maxtracs with this Voter? If so,
>>> how did you interface them?
>> Rear panel connections throught the 16 pin jack. Like most people.
>> In the case of Kenwood TKR-820 Repeaters I had to make my own
>> interface board.
>>
>>> The voter has room for up to 8 sattelite receivers. I have a
>>> bank of UHF Maxtracs all tuned to different frequencies as the
>>> link receivers. They are all identical, and have 16 pins on the
>>> rear. I had planned to use PIN 8 COR and PIN 11 audio to feed
>>> the voter. COR is in ACTIVE HI on the Maxtracs, as such in
>>> the voter.
>> Might be better to build and include a simple logic buffer
>> circuit. One properly selected and applied fet or transitor
>> circuit would probably work very nice.
>>
>>> The trouble I am having is getting PTT through the voter to be
>>> consistant, and by this I mean, only light PTT when there is an
>>> incoming COR signal from one receiver. It seems like the COR
>>> light on the voter is pulsing all the time, and when a good COR
>>> is detected, the COR on the voter goes solid and I can see the
>>> SNR counter go up when I talk through it.
>> You probably need to isolate the COR/COS output line (pin 8) with
>> the simple buffer circuit I mentioned. The description reads like
>> you're getting some type of logic pin dc interaction between the
>> radios and the voter.
>>
>>> Anyone have any ideas?
>> I try not to...
>>
>>
>>> Thanks advance,
>>> Tyler
>>> K0FCQ
>> Reply back to us if you need specific information about how to
>> isolate the radio logic output line from the voter. I myself like
>> active low logic lines where possible.
>>
>> cheers,
>> s.
> 
> Note that the LDG voter does NOT use TTL voltages on the COR inputs !
> This bit me HARD a few years ago.
> 
> Each COR input requires a voltage HIGHER than 6.5 volts (up to 20vDC)
> and going down to ground (less than 1/2 volt) to work properly.
> Yes, it's in the book ... see
> 
> 
> Go to page 8, and I quote:
> 
>  >Active HI means that your receiver COR must produce a positive-going
>  >voltage (6.5 to 20 volts) when the squelch is open (receiving a signal) and
>  >a low-going voltage (0.0 to 4.5 volts) when the squelch is closed 
> (no signal).
> 
>  >Active LO means that your receiver COR must provide a low-going
>  >voltage (0.0 to 4.5 volts) when the squelch is open and a high-going
>  >voltage (6.5 to 20 volts) when the squelch is closed.

That makes some sense too, since the GE voter needs 10V active high. And 
they mean 10; 9.5V won't work.

> I ended up building an interface board that connected several Maxtrac
> receivers to an LDG. The actual setup was to program the MaxTracs
> for active high COR. The signal from each radio fed a 2N transistor
> base through a 4.7 K resistor.  The collectors had 4.7K resistors to +12
> as a pullup resistor on each output.
> 
> The actual radios were 36-42MHz Maxtracs that needed a home... nobody
> wanted them so they were free the 30-36MHz ones end upon 10m, the
> 42-50MHz ones end up on Red Cross or 6m.  The guy that was building the
> system used a converter from 430-440 and fed a TV splitter. Each output
> port fed a Maxtrac. He didn't care about the 75ohm mismatch - the signals
> were strong enough.  The converter was set up so that 439Mhz channels
> showed up on 39Mhz.  End of problem.
> 
> Mike WA6ILQ 
> 

Well, that's an interesting way to do it!

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Mike Morris WA6ILQ]

At 09:06 AM 06/17/08, you wrote:
>
> > I am building a large repeater system here in SE Kansas for SkyWarn
> > and I am wanting to use the RVS-8 Voter.
> >
> > Our system uses Motorola Maxtracs for pretty much every aspect
> > of our giant 15 county coverage repeater.
> >
> > Has anyone successfully used Maxtracs with this Voter? If so,
> > how did you interface them?
>
>Rear panel connections throught the 16 pin jack. Like most people.
>In the case of Kenwood TKR-820 Repeaters I had to make my own
>interface board.
>
> > The voter has room for up to 8 sattelite receivers. I have a
> > bank of UHF Maxtracs all tuned to different frequencies as the
> > link receivers. They are all identical, and have 16 pins on the
> > rear. I had planned to use PIN 8 COR and PIN 11 audio to feed
> > the voter. COR is in ACTIVE HI on the Maxtracs, as such in
> > the voter.
>
>Might be better to build and include a simple logic buffer
>circuit. One properly selected and applied fet or transitor
>circuit would probably work very nice.
>
> > The trouble I am having is getting PTT through the voter to be
> > consistant, and by this I mean, only light PTT when there is an
> > incoming COR signal from one receiver. It seems like the COR
> > light on the voter is pulsing all the time, and when a good COR
> > is detected, the COR on the voter goes solid and I can see the
> > SNR counter go up when I talk through it.
>
>You probably need to isolate the COR/COS output line (pin 8) with
>the simple buffer circuit I mentioned. The description reads like
>you're getting some type of logic pin dc interaction between the
>radios and the voter.
>
> > Anyone have any ideas?
>
>I try not to...
>
>
> > Thanks advance,
> > Tyler
> > K0FCQ
>
>Reply back to us if you need specific information about how to
>isolate the radio logic output line from the voter. I myself like
>active low logic lines where possible.
>
>cheers,
>s.

Note that the LDG voter does NOT use TTL voltages on the COR inputs !
This bit me HARD a few years ago.

Each COR input requires a voltage HIGHER than 6.5 volts (up to 20vDC)
and going down to ground (less than 1/2 volt) to work properly.
Yes, it's in the book ... see


Go to page 8, and I quote:

 >Active HI means that your receiver COR must produce a positive-going
 >voltage (6.5 to 20 volts) when the squelch is open (receiving a signal) and
 >a low-going voltage (0.0 to 4.5 volts) when the squelch is closed 
(no signal).

 >Active LO means that your receiver COR must provide a low-going
 >voltage (0.0 to 4.5 volts) when the squelch is open and a high-going
 >voltage (6.5 to 20 volts) when the squelch is closed.

I ended up building an interface board that connected several Maxtrac
receivers to an LDG. The actual setup was to program the MaxTracs
for active high COR. The signal from each radio fed a 2N transistor
base through a 4.7 K resistor.  The collectors had 4.7K resistors to +12
as a pullup resistor on each output.

The actual radios were 36-42MHz Maxtracs that needed a home... nobody
wanted them so they were free the 30-36MHz ones end upon 10m, the
42-50MHz ones end up on Red Cross or 6m.  The guy that was building the
system used a converter from 430-440 and fed a TV splitter. Each output
port fed a Maxtrac. He didn't care about the 75ohm mismatch - the signals
were strong enough.  The converter was set up so that 439Mhz channels
showed up on 39Mhz.  End of problem.

Mike WA6ILQ 

Re: [Repeater-Builder] Re: Anyone familiar with the LDG RVS-8 Voting system?

[Cort Buffington]

I've found that not every I/O pin in the 16 pin accessory connector is  
created equal, though Pin8, IIRC is one of the "good ones". The bi- 
directional ones are a bit goofy since regardless of input or out put  
configuration, both sets of electronics are connected, but I've had  
more problems with "output only"... Especially the one marked for an  
alarm/siren output.


On Jun 17, 2008, at 11:06 AM, skipp025 wrote:



> I am building a large repeater system here in SE Kansas for SkyWarn
> and I am wanting to use the RVS-8 Voter.
>
> Our system uses Motorola Maxtracs for pretty much every aspect
> of our giant 15 county coverage repeater.
>
> Has anyone successfully used Maxtracs with this Voter? If so,
> how did you interface them?

Rear panel connections throught the 16 pin jack. Like most people.
In the case of Kenwood TKR-820 Repeaters I had to make my own
interface board.

> The voter has room for up to 8 sattelite receivers. I have a
> bank of UHF Maxtracs all tuned to different frequencies as the
> link receivers. They are all identical, and have 16 pins on the
> rear. I had planned to use PIN 8 COR and PIN 11 audio to feed
> the voter. COR is in ACTIVE HI on the Maxtracs, as such in
> the voter.

Might be better to build and include a simple logic buffer
circuit. One properly selected and applied fet or transitor
circuit would probably work very nice.

> The trouble I am having is getting PTT through the voter to be
> consistant, and by this I mean, only light PTT when there is an
> incoming COR signal from one receiver. It seems like the COR
> light on the voter is pulsing all the time, and when a good COR
> is detected, the COR on the voter goes solid and I can see the
> SNR counter go up when I talk through it.

You probably need to isolate the COR/COS output line (pin 8) with
the simple buffer circuit I mentioned. The description reads like
you're getting some type of logic pin dc interaction between the
radios and the voter.

> Anyone have any ideas?

I try not to...

> Thanks advance,
> Tyler
> K0FCQ

Reply back to us if you need specific information about how to
isolate the radio logic output line from the voter. I myself like
active low logic lines where possible.

cheers,
s.





--
Cort Buffington
H: +1-785-838-3034
M: +1-785-865-7206