[arm-allstar] simpleusb / channel driver merge status?

Mon Oct 2 10:07:28 EST 2017

Hi Stanley, Doug,

I do have an isolator on the transmitter, as well as an extra bandpass
filter on both the TX and RX. I haven't tried adding a wattmeter
inline for testing -- that's not a bad idea.

I don't know how to do a "full intermod study" but have a colleague
who has been helping as he can who has started doing some of that; we
have a lot of work to do on the mountain, but just haven't had time to
do it all.  As I've stated several times, I'm mostly trying to
eliminate simple things that I can do remotely at the moment since I
have limited time over the next couple of weeks and I don't know when
the weather is going to turn.

Richard

On Mon, Oct 2, 2017 at 8:44 AM, "Stanley Stanukinos via arm-allstar"
<arm-allstar at hamvoip.org> wrote:
> Richard, you stated you have an isolator on the transmitter. Do you have a second harmonic filter after the isolator? Also have you done a full intermod study on the site including the if frequencies? That may answer some questions.
>
> Stan
>
> Sent from my iPhone
>
>> On Oct 2, 2017, at 9:38 AM, Doug Crompton via arm-allstar <arm-allstar at hamvoip.org> wrote:
>>
>> While they are expensive repeaters in high RF areas should use an isolator
>> (circulator) on the TX line to the duplexor. This not only reduces external
>> RF from entering the the transmitter and producing possible intermod
>> products but also protects the transmitter from a high SWR should something
>> happen to the antenna. Many commercial towers require their use. Stick a
>> watt meter on the antenna and you often see watts of out of band power
>> coming down from the antenna in a high RF area.
>>
>>
>> *73 Doug*
>>
>> *WA3DSP*
>>
>> *http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*
>>
>>
>>
>> On Mon, Oct 2, 2017 at 10:25 AM, "Richard Bateman via arm-allstar" <
>> arm-allstar at hamvoip.org> wrote:
>>
>>> Hi David,
>>>
>>> Yeah, I'm actually getting both of those issues =] I don't think the
>>> echo issue is actually related to desense in this case, though, I
>>> think we have a mixing product somewhere.  I've got an extra bandpass
>>> cavities on both sides and I've done some tests and the sensitivity of
>>> the receiver does not seem to be meaningfully impacted when the
>>> repeater is transmitting.
>>>
>>> The random keying issue could well be something like you suggest;
>>> oddly, only that repeater of the 4 on the same tower is affected and
>>> while I am using some LMR400 on the tower still, it's all very new
>>> (temporary while we make sure our antenna setup is where it will be)
>>> and this antenna is actually the one that *is* using heliax.  I've
>>> also got an isolator on this one, but there isn't on most of the other
>>> ones. If the issue happened all the time it'd be a lot easier to track
>>> down, of course =]
>>>
>>> That does remind me, though, that I don't think I've put the antenna
>>> analyzer on the full antenna system -- I know the antenna itself was
>>> very very good (something like 1.15:1) when I put it up, but I haven't
>>> tested it through the feedline or through the duplexer and I should do
>>> that.
>>>
>>> Lots of things to try, little time to go up on the mountain this week
>>> =] Gotta get part of the house ready for my sister whose family needs
>>> a place to stay for a couple of months as they relocate. Life is
>>> always interfering with my repeater work... *sigh* ;-)
>>>
>>> I appreciate your thoughts and feedback; I'll keep testing and trying
>>> things.
>>>
>>> Richard
>>>
>>>> On Mon, Oct 2, 2017 at 5:32 AM, David McGough <kb4fxc at inttek.net> wrote:
>>>>
>>>> Hi Richard,
>>>>
>>>> If your situation is that the repeater is just randomly generating an
>>>> active COS signal when its transmitter is un-keyed, this is most likely
>>> an
>>>> RF intermod or other interference problem. If you're at a site with
>>>> broadcast transmitters, something intermittently arcing (diode noise) is
>>> a
>>>> likely suspect. Look for (and remove/replace!) any loose, rusted/corroded
>>>> hardware near your RX antenna.
>>>>
>>>> If the repeater is getting back into itself so that you hear an audio
>>>> echo, this is most likely severe desense from the repeater's own
>>>> transmitter. Is the problem reduced/eliminated if you turn the
>>> transmitter
>>>> power down (temporarily)??
>>>>
>>>> Some antennas and types of feedline are more susceptible to PIM (passive
>>>> intermod) generation than others. For example, in general, it's best to
>>>> stay away from LMR style coax---any style that has a tinned braid over
>>>> aluminum foil (dissimilar metals). While LMR coax may work fine when
>>>> initially installed, after a few years, once a little corrosion has
>>>> started between the braid and foil, it starts causing noise problems.
>>> Some
>>>> style of heliax is preferred.
>>>>
>>>> ....Your antenna system needs to be virtually "perfect," of course, if
>>>> you're using a duplexer, or your TX will probably interfere with the RX.
>>>>
>>>> Without knowing more about your RF setup, it's hard to do more in depth
>>>> diagnostics??
>>>>
>>>>
>>>> 73, David KB4FXC
>>>>
>>>>
>>>>> On Sun, 1 Oct 2017, Richard Bateman wrote:
>>>>>
>>>>> Yeah, I'm using the URIx.  I'm having a couple of issues, but the one
>>>>> I'm trying to deal with right now is basically that there is some kind
>>>>> of noise that keeps keying up the repeater and we can't figure out
>>>>> where it is coming from. It might well just be that it's RF noise and
>>>>> we need to track it down, since I hear it when the repeater's squelch
>>>>> opens and there is no signal to listen to, but on the spectrum
>>>>> analyzer it's not strong enough to come out of the noise.
>>>>>
>>>>> Sometimes it'll sit there kerchunking over and over again, multiple
>>>>> times per second, despite the PL tone on the receive, and other times
>>>>> it's quiet as you could ask for. Putting an extra ground wire as you
>>>>> suggest sounds like it'd be worth a try to me =]
>>>>>
>>>>> One reason I've been considering trying dsp-based is to find out for
>>>>> sure if the issue is in the RF signal or if it's in the CTCSS/COR
>>>>> signalling when they shouldn't (for whatever reason, whether the
>>>>> radio, which is a TKR-750 version 1, or some electrical issue like a
>>>>> ground loop).
>>>>>
>>>>> Richard
>>>>>
>>>>> On Sun, Oct 1, 2017 at 7:44 PM, David McGough <kb4fxc at inttek.net>
>>> wrote:
>>>>>>
>>>>>> Hi Richard,
>>>>>>
>>>>>> Are you using a URI or URIx audio adapter?  If so, I've had superior
>>>>>> results by adding an extra, heavy-gauge ground lead to the URI. Then,
>>> I
>>>>>> directly connect this lead to the repeater chassis--a screw on a
>>> Kenwood
>>>>>> TKR repeaters...This has been my #1 ground-loop solution.
>>>>>>
>>>>>> Here are a few sample photos:
>>>>>>
>>>>>> https://hamvoip.org/kenwood-TKR/P1030817.JPG
>>>>>> https://hamvoip.org/kenwood-TKR/P1030820.JPG
>>>>>>
>>>>>> Test TKR-750-2 repeater on bench:
>>>>>> https://hamvoip.org/kenwood-TKR/P1030831.JPG
>>>>>>
>>>>>> ALSO -- on the TKR750/850 repeaters, make sure to notice that the
>>> 25-pin
>>>>>> accessory plug has separate analog and digital grounds!
>>>>>>
>>>>>> If you've got RF or other noise issues with simpleusb telemetry, I
>>> doubt
>>>>>> switching to usbradio DSP-based signaling will fix anything. Try
>>> running
>>>>>> the TX into a dummy load and test, if possible.
>>>>>>
>>>>>> 73, David KB4FXC
>>>>>>
>>>>>>
>>>>>>> On Sun, 1 Oct 2017, "Richard Bateman via arm-allstar" wrote:
>>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> I've been having some issues that I'm starting to suspect might be
>>>>>>> related to RF getting into my interface cables triggering my COR and
>>>>>>> CTCSS lines (not in any way convinced, but it's on my list of
>>>>>>> suspects) and have been toying with the idea of using usbradio
>>> instead
>>>>>>> of simpleusb for awhile; last time I did that the audio was kinda
>>>>>>> crappy, so I switched to simpleusb.
>>>>>>>
>>>>>>> While looking around I noticed that there is a "TODO" on the hamvoip
>>>>>>> page about merging the channel drivers, which I assume might be
>>>>>>> something along the lines of using DSP for COR and CTCSS detect but
>>>>>>> using the other audio for actual TX?
>>>>>>>
>>>>>>> Anyway, I'm just wondering what the status of that is and if there is
>>>>>>> any way I can help with the efforts; it would help me out a lot on
>>>>>>> several different projects.
>>>>>>>
>>>>>>> Richard
>>>>>>> _______________________________________________
>>>>>>>
>>>>>>> arm-allstar mailing list
>>>>>>> arm-allstar at hamvoip.org
>>>>>>> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>>>>>>>
>>>>>>> Visit the BBB and RPi2/3 web page - http://hamvoip.org
>>>>>>>
>>>>>>
>>>>>
>>>>
>>> _______________________________________________
>>>
>>> arm-allstar mailing list
>>> arm-allstar at hamvoip.org
>>> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>>>
>>> Visit the BBB and RPi2/3 web page - http://hamvoip.org
>>>
>> _______________________________________________
>>
>> arm-allstar mailing list
>> arm-allstar at hamvoip.org
>> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>>
>> Visit the BBB and RPi2/3 web page - http://hamvoip.org
>
>
> .
> _______________________________________________
>
> arm-allstar mailing list
> arm-allstar at hamvoip.org
> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>
> Visit the BBB and RPi2/3 web page - http://hamvoip.org