Forrest,

What’s the down size of making the change for you?

 

Best regards,

Brandon Yuchasz

GogebicRange.net

www.gogebicrange.net <http://www.gogebicrange.net/> 

 

From: Af [mailto:af-boun...@afmug.com] On Behalf Of Forrest Christian (List 
Account)
Sent: Wednesday, June 03, 2015 3:22 PM
To: af
Subject: Re: [AFMUG] ePMP sync differences CMM3 vs CMM4.

 

I agree...buy lots of packetflux gear instead.  ;)

I guess my implied question was more:   "Since the ePMP seems to treat the 
internal GPS and CMM4 timing identically, and the syncinjectors produce CMM3 
timing which creates additional complications in mixed internal 
GPS/Syncinjector network, is there value in me bothering with a switch to 
switch between CMM3 and CMM4 timing in the syncinjectors?".

The situation I see is where you have a network with syncinjectors, and for 
whatever reason the sync source fails on one of the injectors.  You go into the 
ePMP and tell it to use the built-in GPS.   Now you're in the situation that 
you have to go and mess with front and back settings to match the 
recommendation in the manual since the AP's you just switched are now on the 
opposite timing.   If the syncinjector could be set to CMM4 timing, this 
wouldn't be necessary - swap the sync source, and you're still good to go.

-forrest

 

On Wed, Jun 3, 2015 at 2:13 PM, Josh Luthman <j...@imaginenetworksllc.com> 
wrote:

>Thoughts?

 

Don't buy a CMM4.




 

Josh Luthman
Office: 937-552-2340
Direct: 937-552-2343
1100 Wayne St
Suite 1337
Troy, OH 45373

 

On Wed, Jun 3, 2015 at 4:07 PM, Forrest Christian (List Account) 
<li...@packetflux.com> wrote:

On the cambium ask the synchronization experts thing I'm doing someone pointed 
out the section in the ePMP manual talking about frequency reuse. I had to go 
look since I had somehow missed that section.   In case you haven't seen it, 
there's a deep discussion about the proper settings when you have a "mixed" 
network of internal GPS, CMM3 and CMM4.   (See Page 94 in the current release). 
  I admit my ignorance and I hadn't seen this yet, but.....

All I have to say is this:  WTF Cambium?

Ok, I know the dirty little secret that the CMM3 and CMM4 produce different 
timing pulses.   Obviously different enough that it matters in the ePMP world.  
 But the difference is easy enough to fix...  add a fixed amount of delay which 
varies based on the timing source.   They already have to delay the GPS timing 
signal to match the CMM4.    Why not delay the two sources which are 'early' to 
match the 'late' source?   Or even better, fix the CMM4 so it matches every 
other sync source on the planet - I'm shocked this hasn't already been done.   
Ok, I get it, it might be a hardware limitation which prevents one or both of 
the solutions.   But come on, really?

For the record the syncinjectors currently produce "CMM3" timing, not "CMM4".  
Since it's obvious that the difference matters now, I'm considering adding a 
software witch which allows this to be configured so you don't have to deal 
with a 'mixed' timing source since it seems like a CMM4 and internal GPS are 
identical.  This should permit better operation when you have to switch between 
an internal GPS and a SyncInjector.

Thoughts?


-- 


Forrest Christian CEO, PacketFlux Technologies, Inc.

Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602

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-- 


Forrest Christian CEO, PacketFlux Technologies, Inc.

Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602

 <mailto:forre...@imach.com> forre...@imach.com |  <http://www.packetflux.com/> 
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