Hi Roger.
In the recent past the squelch appears to have been set fairly high. As witnessed by the repeated signals being essentially noise free. It is now much easier to track the correct uplink on 2m as the doppler shift is small compared to the 12.5kHz or so (a guess) bandwidth of the ISS receivers IF filter.
Unfortunately, I believe the D800 is unable to operate with the squelch open due to overheating problems. Not that anyone is complaining, this ARISS operation is great!
But the D800 is not a purpose built satellite repeater. Given a choice, a SO50 type approach would give easier access for operators while saving power / heating and RF pollution. A CTCSS detector that initiated a timer, or perhaps a system that simply allowed the repeater to stay open for 10 or 15 seconds after loss of the tone would allow people to 'net' onto the correct uplink frequency, or hear when their signal had a fade or collision with another station.
I suppose the ARISS equipment will be upgraded at some point in the future and maybe some dedicated hardware with simple to operate controls for the crew (and remote commanding from the ground) will overcome these minor problems with an otherwise very successful system.
Still, 5 Watts downlink is quite amazing and unlike any conventional satellite we have. Where's my 2m amp......
Regards
David G0MRF
In a message dated 06/01/2009 10:07:23 GMT Standard Time, rogerkola@aol.com writes:
An interesting thought...could they have the squelch engaged while also requiring tone? I personally haven't been able to get in on 80 degree passes over New England with 25 watts and an omni at 5:30 AM local time.
Reception is just fine, but there are a lot of "empty" spaces in between contacts that could be collisions I guess...
Roger WA1KAT
Hi David...
Thanks for your input...I was just confirming that I was observing the same thing...I know that Miles, WF1F, has explained the lack of gravity eliminates inductive cooling on the rigs, causing the higher temperatures they are seeing.
I actually have no complaints here...I have cards from several contacts with the Station and one with MIR that I can look at during passes ;-)...the U/V repeater was also very good to me and UNPROTO during packet operations is plenty of fun.
I was just throwing in my 2 pence as to why this particular mode was presenting some new challenges...
I have the amp and a beam, but I'd just as soon leave them out of line to give others an opportunity...(besides our pass times here are still in the middle of the night as far as I am concerned ;-)
Best 73 es DX
Roger WA1KAT ----- Original Message ----- From: G0MRF@aol.com To: RogerKola@aol.com ; amsat-bb@amsat.org Sent: Tuesday, January 06, 2009 12:57 PM Subject: Re: [amsat-bb] Re: Still not getting into the ISS...
Hi Roger.
In the recent past the squelch appears to have been set fairly high. As witnessed by the repeated signals being essentially noise free. It is now much easier to track the correct uplink on 2m as the doppler shift is small compared to the 12.5kHz or so (a guess) bandwidth of the ISS receivers IF filter.
Unfortunately, I believe the D800 is unable to operate with the squelch open due to overheating problems. Not that anyone is complaining, this ARISS operation is great!
But the D800 is not a purpose built satellite repeater. Given a choice, a SO50 type approach would give easier access for operators while saving power / heating and RF pollution. A CTCSS detector that initiated a timer, or perhaps a system that simply allowed the repeater to stay open for 10 or 15 seconds after loss of the tone would allow people to 'net' onto the correct uplink frequency, or hear when their signal had a fade or collision with another station.
I suppose the ARISS equipment will be upgraded at some point in the future and maybe some dedicated hardware with simple to operate controls for the crew (and remote commanding from the ground) will overcome these minor problems with an otherwise very successful system.
Still, 5 Watts downlink is quite amazing and unlike any conventional satellite we have. Where's my 2m amp......
Regards
David G0MRF
On Tue, 2009-01-06 at 12:57 -0500, G0MRF@aol.com wrote:
Hi Roger.
In the recent past the squelch appears to have been set fairly high. As witnessed by the repeated signals being essentially noise free. It is now much easier to track the correct uplink on 2m as the doppler shift is small compared to the 12.5kHz or so (a guess) bandwidth of the ISS receivers IF filter.
So 5kHz steps should be "close enough"?
Still, 5 Watts downlink is quite amazing and unlike any conventional satellite we have. Where's my 2m amp......
Well I can't use more than 10W anyway, and the only transceiver I have that does CTCSS has only 5W output.
I wonder if it's worth pointing the 6-element quad at it? I haven't really used that yet, since I don't have a tower to put it on, and it's a bit awkward to use hand-held ;-)
Gordon
participants (3)
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G0MRF＠aol.com -
Gordon JC Pearce MM3YEQ -
Roger Kolakowski