[App_rpt-users] Long Squelch tail problem

Sat Oct 5 14:24:17 UTC 2013

GM300s work very well with dsp squelch. I am using 7 of them here.  There
is a jumper inside the gm300 that has to be set correctly to get un-de-emp
audio out on the connector that is on the back of the radio.  Check the
service manual for your exact model as there are several different board
layouts but I believe that all of them have a similar jumper.  Also be very
careful about stray capacitance on the wires between the GM300 and the USB
device as even a very small capacitance to ground can roll off the high end
that is needed for the dsp squelch to work correctly.
For other radios I have always been able to do surgery on the radio and
pick off discriminator audio directly from the discriminator chip and take
it directly to the usb device or to the RTCM or voter board.

Chuck

On Sat, Oct 5, 2013 at 9:07 AM, Ken <ke2n at cs.com> wrote:

> I have found that, if the noise test does not pass, then DSP squelch
> operation will be generally unsatisfactory. You can fiddle with the
> “rxsquelch” setting so that it closes reliably, but then you will find it
> cuts out people in mid-sentence, when their signal seems quite copy-able
> (very annoying).  Best thing to do in that case is to use hardware squelch.
> With an HT, it’s problematical, of course. You have to “operate” on the
> radio and void whatever warrantee.  There is only one amateur HT I am aware
> of that had the COS signal available as an external signal (in the
> microphone connector I think).****
>
> ** **
>
> 73****
>
> Ken****
>
> ** **
>
> ** **
>
> ** **
>
> *From:* Bill Hurlock [mailto:bill.hurlock at cpcomms.com]
> *Sent:* Friday, October 04, 2013 12:18 PM
> *To:* Tim Sawyer
>
> *Cc:* app_rpt-users at ohnosec.org list
> *Subject:* Re: [App_rpt-users] Long Squelch tail problem****
>
> ** **
>
> The 736R seems to be lacking in the HF noise area as I can’t make it to
> the 27000 number the program is looking for. It almost gets there. About
> 26231. I’ll have to run a SQ open point test on the radio and see where the
> SQ opens. I have the test gear to do that.****
>
> Thanks****
>
> ** **
>
> *Bill Hurlock*
>
> ** **
>
> *From:* Tim Sawyer [mailto:tim.sawyer at me.com <tim.sawyer at me.com>]
> *Sent:* Friday, October 04, 2013 10:49 AM
> *To:* Bill Hurlock
> *Cc:* app_rpt-users at ohnosec.org list
> *Subject:* Re: [App_rpt-users] Long Squelch tail problem****
>
> ** **
>
> Wouxon HTs seem to do that even on systems with perfectly good squelch.
> Maybe they slowly reduce the transmit power or something. It seems worse
> when you're close to the receiver. ****
>
> ** **
>
> As far as your usbradio long squelch tail problem; some radios just don't
> have enough high frequency noise to drive the DSP properly. In that case
> you have to use simpleUSB.****
>
> ** **
>
> Also please note that even with a properly working DSP squelch quickly
> kerchunking will produce a long squelch tail... just like MICOR squelch
> will do. ****
>
> --****
>
> Tim****
>
> :wq****
>
> ** **
>
> On Oct 4, 2013, at 7:05 AM, Bill Hurlock <bill.hurlock at cpcomms.com> wrote:
> ****
>
> ** **
>
> I have tried tightening the SQ but then I start to have decode issues with
> some of the connecting radios. The current signal strength reading, no
> carrier present, is 776 and SQ setting is 900. This does eliminate the SQ
> tail but I’m sure this is going to affect RX sensitivity over all being so
> high. There appears to be a very narrow range of SQ levels that provide no
> SQ tail and decode is fair. Most problematic are the Wouxon radios.****
>
>  ****
>
> *Bill Hurlock*****
>
>  ****
>
> *From:* Corey Dean [mailto:n3fe at repeater.net]
> *Sent:* Friday, October 04, 2013 12:30 AM
> *To:* Bill Hurlock; app_rpt-users at ohnosec.org
> *Subject:* RE: Long Squelch tail problem****
>
>  ****
>
> Have you tried increasing the squelch level?  What is the current squelch
> level?****
>
>  ****
>
> Corey  N3FE****
>
>  ****
>
> *From:* app_rpt-users-bounces at ohnosec.org [
> mailto:app_rpt-users-bounces at ohnosec.org<app_rpt-users-bounces at ohnosec.org>
> ] *On Behalf Of *Bill Hurlock
> *Sent:* Thursday, October 03, 2013 7:46 PM
> *To:* app_rpt-users at ohnosec.org
> *Subject:* [App_rpt-users] Long Squelch tail problem****
>
>  ****
>
> I had to go back to my URI interface and my FT-736R. I have it set up to
> do tone encode and decode using the URI. All the encode and decode are
> working however when I unkey there is a squelch tail that lasts about 1 to
> 2 seconds. I’m allowing the URI to determine COR thru DSP. The connections
> are setup for raw audio both ways with the node supplying the pre and de
> emphasis. I have played with the settings but nothing changes the problem.
> It isn’t a consistent duration of tail. I know it is in tone decode mode
> because if I turn tone off on the portable I can’t open the squelch thru
> the node. Anyone have any ideas……****
>
>  ****
>
> *Bill Hurlock*****
>
> *CPCommunications*****
>
> *856-234-1661 Office*****
>
> *856-264-1010* <http://www.totalrf.com/>* **Cell*****
>
> *www.cpcomms.com* <http://www.cpcomms.com/>****
>
> *WA2TQI*****
>
>  ****
>
>
> --
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