[Skimmertalk] disabling USB connection

[Bob Wilson, N6TV]

Pete,

I guess I don't understand what problem you are trying to solve by "opening
the data line in the USB cable" (which isn't really possible).

My Pixel Loop is only 20' from the shunt-fed tower on 160m (1500W).  I use
a combination of a Front-End saver and a pre-amp power disconnect via PTT
to protect it during transmit, plus a Bad Call List in the Aggregator.
 This combination seems to work fine.

73,
Bob, N6TV

On Sun, Jun 23, 2013 at 6:11 PM, Pete Smith N4ZR <n4zr at contesting.com>wrote:

> Yep, been there, and been doing that for years, Bob - in my setup, PTT
> removes voltage from the active antenna, which opens a relay to the whip,
> and also removes DC from my preamp.  That protects the hardware just fine,
> and in my case, where the transmitting antennas are ~500 ft from the RX
> antenna, and ~200 feet from the RX itself, is quite adequate. I asked the
> question more for the guy whoseSkimmer antenna and TX antennas are within
> 50 feet of each other.
>
> In fact, the RBN Aggregator already does this in software with a "bad call
> list".
>
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network at
> http://reversebeacon.net,
> blog at reversebeacon.blogspot.com.
> For spots, please go to your favorite
> ARC V6 or VE7CC DX cluster node.
>
> On 6/23/2013 7:00 PM, Bob Wilson, N6TV wrote:
>
>> On Sun, Jun 23, 2013 at 9:14 AM, Pete Smith N4ZR <n4zr at contesting.com
>> >wrote:
>>
>>  It occurs to me that one way to mute a QS1R, SDR-IQ or similar receiver
>>> might be to open one or the other (or both) data lines in the USB cable.
>>>   This probably is 'way too simple - does any of you know if the USB
>>> drivers
>>> used on motherboards would tolerate this without throwing an error?
>>>
>>>  It sounds like you want to mute the data to prevent "images" of your
>> transmitted signal from being spotted? It's probably much simpler to do
>> that in software (e.g. use a "reject" list to eliminate every variation of
>> your own callsign being spotted by the local skimmer).
>>
>> The real need, of course, is to open or protect the front end of your SDR
>> whenever you transmit.  Opening or stopping the USB line will not protect
>> your SDR. :-)
>>
>> Some RX antennas using remote Pre-Amps (e.g. active Rx Loops or short
>> vertical whips) provide a way to quickly remove pre-amp power using the
>> PTT
>> line on the radio.  That's very effective, and much better than trying to
>> do it in software or via USB commands or tricks.
>>
>> 73,
>> Bob, N6TV
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