I have been aware of n0an's trick for some time, but unless someone can find a command that will invoke this with a simple macro, I find it too much of a hassle do do frequently. I was never able to find a command that would invoke A=B via HRD or Commander, so gave up.
On Fri, Jun 19, 2009 at 5:21 PM, J. Moen<j...@jwmoen.com> wrote: > > > This note is for users of the TS-2000 who could use the ability to reduce Rx > bandwidth to as narrow as 50 hz. > > Andy K3UK asks about mitigating the problem of a strong signal near your > weaker target signal. Phil points out IF DSP is better than AF DSP, but a > technique described by Hans N0AN will help quite a lot. The following is > all by N0AN from notes on another reflector. > > The DSP filtering in the TS-2K is quite good. One trick that a > lot of people don't seem to use or know about is for superb > reception of psk31/rtty etc. > > Run the radio in split mode. Here is how to do it. > > 0. Select your favorite psk31 freq on the "A" vfo > (left side, receive, USB) > > 1. Select SPLIT vfo's. > 2. Make "A" your left VFO (arrow points to left by the "A") > 3. Make "B" your right VFO (arrow points to the right by > the "B") > 4. Hit the A=B button to put both vfos on the same freq > and mode. > 5. Select CW for your receive mode (hit cw button) > 6. Set your bandwidth control to 2000 hz for now > 7. Set your shift control to 900 hz for now > > 7a. Turn XIT on and set it to -800 hz (this puts your > transmit and rx on the same freq, even though you > have different modes selected (cw on rx, usb on tx) > > 8. Press and hold the TF-set button, and while holding > it, hit the SSB button..this sets the transmit vfo in > the SSB mode. > > This may sound like a lot, but it is actually quite simple, > and you only have to do it once! > > You are now set to receive on VFO A (left side) in CW > and to transmit on VFO B(right side) in SSB. Due to > setting XIT to -800 Hz, they are on EXACTLY the > same frequency. > > Now...as long as you use the receive window of your > software (like MixW) to change frequency by selecting > different signals on the waterfall/spectrum by > clicking with the mouse, you don't have to do any > retuning! You have approximately 1500 hertz of bandwidth > to play with, without touching any knobs. > > So...what does this get you? You can now use the filter > width and shift controls (lower left side of front panel) to > allow you to receive in any bandwidth from 2000 hz > down to 50 hz!!! You have virtual privacy when you > narrow the receive filter down to 50hz, believe me. > > I set my shift control to about 900 hz, because I want > to be able to copy psk31 signals down to about 350 hz > and up to about 1500 hz. If you choose 900 hz for > your shift, you can still copy most of the band. You > can click anywhere in the waterfall/spectrum on a signal > and instantly begin copying, no knobs, no messing > around, but perfect reception. Then it is a simple matter > to start closing down the rx bandwidth with the left knob. > Reduce it one click and you drop from 2000 hz wide > to 1000 hz....all the way down to 50 hz if you want. > > Now...as you start reducing the bandwidth significantly > with the left knob, you will need to adjust your shift to > correspond to what the station you are listening to tone > freq's actually are...in other words, if you reduce things > from 2000 to 600 hz, and you were listening at 1100 hz, > you will lose the rx signal until you adjust the shift knob > to a bit closer to 600 hz (assuming the station you are > listening to is on 600 hz in the waterfall/spectrum > display.) > > While all this might sound overwhelming, it is really > quite simple and one gets good at it. > > --------- Addendum ---- from followup notes by N0AN > Simply put, two things control how you receive a signal with this setup: > > a. The receive bandwidth (left knob) > b. The receive shift (right knob) > > The ideal is to set the receive shift to the center freq of the signal you > are listening to, BUT, the wider you have you bandwidth set, the more > tolerant things are to having your shift off. > When things are "wide open" at 2000 hz, you can set the shift to 900 hz and > forget it. When you start to tighten down the bandwidth, you need to move > the shift center freq (right knob) to more closely agree with where you are > actually listening. > > ============================= > > If you find it necessary to change the radio receiver VFO frequency, just do > this after tuning the radio to a new frequency: > > Hit A=B button > Press and hold TF-Set > Hit the SSB button (while holding the TF-Set button...let up on the TF-Set > after you have tapped the SSB button. > > You have now done the following: > > Set the A and B VFOs to the same freq and mode > Reset the B vfo to USB (it got changed to CW when you hit the A=B button) > > I find I don't have to do this very often as 99% of the psk31 activity is on > a specific band of frequencies centered at about 14.070 or 14.071 (cw > receive). At 50 hz wide, that couple of kilohertz is a LOT of bandwidth, so > you don't have to retune very often...you just use the waterfall/spectrum > display and your mouse click for tuning. > > I've used this trick successfully with both a TS-870 and the new TS-2000, > and it works beautifully. QRM on psk31 is a thing of the past with the > outstanding dsp filtering in this radio. Once one learns the method for > setting things up that I described above, it is psk31 heaven! At 50 hz > bandwidth (and your shift set right on the money), there is no qrm. > > 73, > > .hasan, N0AN.. > > p.s., notice when you close down the rx bandwidth your waterfall/spectrum > display changes dramatically, showing the actual shape factor of your > received bandwidth....a nice idication of how well the dsp filtering is > working in the TS-2000 > > ----- Original Message ----- > From: Andy obrien > To: digitalradio > Sent: Thursday, May 28, 2009 5:08 PM > Subject: [digitalradio] Really beating the AGC issue with PSK ? > > From time to time we have had discussions here about the problem with > PSK (and other modes) when a strong stations appears to grab the > waterfall and wipe out all the other stations within a 2-3 Khz range. > Because of this phenomenon, when I purchased a new rig, I looked for > one that could have AGC totally off (when needed) and one that can > employ narrow DSP filtering. I must say that I have not really solved > this issue . I can see a marginal difference with AGC turned off but > strong signals still essentially desensitize other stations in the > waterfall. The DSP features do better and I can get rid of the > phenomena by turning to a narrow filter. However this does not help > if the offending station is with 300 - 500 Hz ( a lot when dealing > with narrow digital modes). > > Does anyone have any advice on how to once and for all solve this > issue? My rig is a TS2000 > > Andy K3UK > > . > >
