[Premium-Rx] Utility Monitoring Receiver

[sm0aom at telia.com]

This is quite difficult.

I have designed the watchkeeping system för the air-ground HF provider Stockholm Radio, and generally speaking, scanning receivers with syllabic squelch are not
used in professional systems due to the quite high risk of missing incoming calls with low S/N.

For less critical applications, it is possible to use this approach, and ages ago the ICOM M-700 and M-710 marine transceivers were used for similar purposes.
However, these have a relay-switched lowpass filter bank in the transmitter which has to be disabled if silent operations are a necessity.

Also, the scanning cycle composition and the dwell time on each channel will be critical parameters,together with the properties of the syllabic squelch while changing channels.
Any transients in the noise level should not open the squelch and stop the scanning.

The outcome of this endeavour will very much be dictated by the properties of the syllabic squelch, which I suspect differs among the various realizations.

73/
Karl-Arne
SM0AOM


----Ursprungligt meddelande----
Från : spencer12345 at msn.com
Datum : 2016-01-08 - 06:07 (UTC)
Till : premium-rx at mailman.qth.net
Ämne : [Premium-Rx] Utility Monitoring Receiver

All-
I have a highly technical friend who has long been involved in radio communications who has asked a question of me that I thought I would post to the list and see what others might recommend.

Here is his question, along with a few qualifiers.

He is looking for a quality HF receiver that can be used to monitor a number (let's say 30) of HF frequencies. These will be spread across the 4-22 MHz range. These will all be placed in memory and the receiver left to scan. He will use a broadband loop for his receive antenna.

He wants receiver audio squelched, and the receiver to stop and monitor SSB utility traffic, mainly aeronautical traffic (his wife works for a European air carrier and he has some interest in this traffic as a result). This seems to call for syllabic squelch rather than noise squelch, especially given that the receiver will see widely varying levels of band noise as it scans the wide frequency range he is interested in.

He also does not want the noise of opening and closing relays in the receiver preselector. His goal is silence when not receiving traffic.

His goal is to spend around $1000 USD for a used unit. My thought was that using one of the transceivers designed for 'commercial' mobile or base station use may be his best choice. Something like a Micom/Mobat, Codan, or Barrett. He does not need a receiver with a tuning knob since he already has this capability.

I have not used any of these radios personally, though do have a Motorola Micom receiver that has very nice syllabic squelch action. 

So what would readers recommend? I am pretty sure the Motorola/Mobat gear all have syllabic squelch but don't know if there are relay switched front end filters. I assume the Ausie gear also has good SSB squelch, but don't have direct experience.

Thanks in advance for your feedback on this. I realize it's a bit 'on the edge' of a premium rx topic!

Spencer K7SLB
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