Re: G0MRF downconverter
I really fail to see where you are coming from. I never suggested for one moment that the IC-706MK2G could transmit and receive at the same time. All I want is full transceive, marrying up the uplink IF and the downlink IF as being on the same frequency on the radio, obviously the RIT will almost certainly have to be used to some extent.
The signal strength into the transponder can be monitored on the WEB SDR from Goonhilly..... or if that goes down I have a second dish with stable LNB I can feed into a dongle at 739MHz.
Just out of interest on the uplink I use an SG Labs transverter into an SG Labs 20w amp throttled back to 15w. Uplink antenna is a so called ‘professional Super Cannon’ - a 16 turn helix made for the drone market with my modification of an arrow shaped tab inserted at the first quarter turn for the amp to ‘see’ a proper 50ohm.
The amplifier and 25MHz reference sit on the windowsill the other side of the shack with the helix on the other side of the wall. As soon as I hopefully get some success with a new 25.788461++++ MHz reference using the Si clock chip I will let everyone know. I am not one hell of a know-all, far from it, I will have to get my good friend Martin Waller to program the ‘NANO’ or even a ‘MICRO’....that’s beyond my 70 year old brain these days.
I’ve just thought, if I do that I will need a bias tee ! 12v for the LNB presently derived from the MRF downconverter.
Best regards to all,
Colin de G8LBS, Ipswich.
Sent from Mail for Windows 10 Pro
From: Paul Randall G3NJV
Sent: 06 September 2020 21:57
Subject: Re: [UKMicrowaves] G0MRF downconverter
The IC706 cannot transmit and receive at the same time. You need an IC-821 or IC-910 or another "satellite" rig for that. "Full duplex mandatory" is not about having a full duplex communication circuit, it is specified because you are accessing a linear transponder and MUST monitor your uplink in real time to ensure you are not too "hot". You can check your uplink using the web SDR at Goonhilly and use a traditional half duplex "press to talk" rig for your communication circuit - easy.
Satellite DID virtually replace undersea cables on thick routes - e.g. carriers put up to increase capacity at Christmas to USA/Canada/Australia had thousands of telephone circuits - an order of magnitude increase over coaxial cables. Then fibre happened.
Hearing noises coming back at you while you are talking makes people hesitate and pause their speech, it is after all, POLITE to do so; upbringing, social skill, we learn to do this to participate in normal conversations. A common problem on HF marine circuits that pre-dated satellite, so possibly not so much an issue of delay. I have recordings of conversations on HF completely halted by "politeness" even though the "communication speech circuits" are fully operational - sometimes the "operator" had to break in to get things moving again. Mastering this issue was, and still is today, a MUST for professionals, Coastguard, Air traffic control, etc - it is largely a case of becoming a bit boorish and completing your sentence no matter what you hear - ears off mouth on. Yes, you might have full duplex, but to communicate effectively you may (mentally) need to use it like half duplex.
Thats my 2p worth
From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of PAUL NICKALLS via groups.io <paulnick@...>
The delay is why the telephone system will not use 2 satellite links on a telephony circuit. It was thought that satellites would replace undersea cables. However
On 06/09/2020 15:39, Andy G4JNT wrote: