Fonfident what everyone needs is another opinion, I am going to throw my two cents in: I don't see beaconing any more as brodcasting than calling CQ. ________________________________________ From: amsat-bb-bounces@amsat.org [amsat-bb-bounces@amsat.org] on behalf of Daniel Lind [kf1buz@gmail.com] Sent: 05 June 2011 22:42 To: 'Jeremy Bomkamp'; amsat-bb@amsat.org; 'Kevin Deane' Subject: [amsat-bb] Re: Broadcasting

All, If I am broadcasting with my beacon on, I am sorry, if I see a friend pop on and I send him a message, sorry again.

I am a newish ham and built my own cable to make my ft7800 able to do packet. No my car it has a tiny track and as it is parked it sends out a burst, just like all the aprs repeaters on 144.390 broadcasting away to any one who will listen.

I am thinking that if you are upset that I am taking the seconds away from you at 5am PST to send a message on something that I built and out the J pole I made. Again I am sorry, but I think that isn't the issue. It's the fact that we are doing it with low end equipment that a Tech license allows us to use. When the new crew arrive on the 9th, there will be 2 more ham guys, and you can bet your $$$$$$$$ equipment that I will take out my ft 60 and make a nice QSO like I have before.

Sorry for the rant but, there ya have it.

PM me if you really have any issues.

Daniel KF1BUZ

-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Jeremy Bomkamp Sent: Sunday, June 05, 2011 5:57 PM To: amsat-bb@amsat.org; Kevin Deane Subject: [amsat-bb] Re: Broadcasting

Bash Kevin if you want, but isn't 99.9% of all APRS broadcasting? You never really expect a response from anyone, and what true purpose does the digi on the ISS perform? Most of it is amateurs BROADCASTING their locations, no emergency traffic, the only real protocol is to ID and no swearing which both KF7MYK and KF7BUZ complied with, at least it wasn't HI HI, roger, roger _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

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Bob,

Guess the APRS dilemma was like splitting the atom. The real use and the unintended use.

Could a system like the ISS be switched to a PSK31 or similar mode in the future? How well would PSK work with Doppler etc? I use it on HF, but was wondering if FM and satellites could be feasible. I believe this was mentioned as possibly being part of Fox's system.

73 Greg N3MVF

-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Bob Bruninga Sent: Monday, June 06, 2011 2:41 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: Broadcasting

but isn't 99.9% of all APRS broadcasting? You never really expect a response from anyone... Most of it is amateurs BROADCASTING their locations, no emergency traffic...

That is simply because too many people were completely mislead into thinking of APRS as a vehicle tracking system which is just wrong. It was nothing of the kind. It evolved from the 1980's desire to get away from one-on-one packet BBS's with NO human contact back to HUMAN-to-HUMAN live information exchange.

But then in the mid 1990's GPS came out and so did a lot of stupid trackers and now we are stuck with this light's-on-nobody-home scenario in a lot of people's minds. See how wrong these assumptions are: http://aprs.org/APRS-tactical.html

My focus in APRS has always been about live contact. That is why now all new APRS radios not only communicate the position of the other stations, but also their voice contact frequency in every packet. See: http://aprs.org/localinfo.html

Bob, Wb4APR

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Sounds just like yet another "anti wide" rant to me.

John, W0JAB

Greg, you're overlooking something - the time dimension.

Yes, packet is a one-at-a-time affair, but those packets move quickly - 1200bps vs 31bps for PSK31. So, each station only has the bird tied up for a short period of time. You could think of it as a form of time division multiplexing. 73 de AJ4MJ On Mon, Jun 6, 2011 at 7:43 PM, Greg Dober almetco@comcast.net wrote:

Hi John,

I'm not so sure it's an anti-wide rant. It is a discussion on a possible way to get more efficient use from the limited bandwidth and power on the bird. I love playing with RTTY on HF and packet on VHF, but when you head down to 14.070 and see all the stations on the sliver of band qso'ing, it seems appealing to use to eliminate overcrowding on a satellite.

Greg N3MVF

-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of John Becker Sent: Monday, June 06, 2011 7:23 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: PSK v. APRS

Sounds just like yet another "anti wide" rant to me.

John, W0JAB

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My pet hate is AX.25 1200bps FM which every satellite seems to use, it uses too much bandwidth, too much power and has no forward error correction.

BPSK systems such as that to be used on ARISSat-1 can provide 1000 bps with error correction in less than 1/10th the bandwidth.

But the reason AX.25 1200bps FM is still used for new satellites is because there's so much infrastructure, TNC's, PC software etc, already inplace, it's the easy option.

Currently there is no single standard for sending data using BPSK not even the data rate is standardized. I believe the BPSK telemetry on FOX will use a different standard to ARISSat. FUNcube and UKube-1 will also use different versions running 1200bps and 9600bps respectively.

Personally I think 9600bps BPSK will be the one to go for in the long term but none of these BPSK systems are flying yet. So until they are and are proven to work in space I think AX.25 1200 FM will continue to be used.

Getting new equipment on the ISS has an incrediably long lead time and of course relies on someones goodwill to pay some $5,000 a kilo freight charges, so realistically I can't see any significant changes to the ISS equipment for sometime to come.

73 Trevor M5AKA

--- On Mon, 6/6/11, Greg Dober almetco@comcast.net wrote:

Bob,

Guess the APRS dilemma was like splitting the atom.  The real use and the unintended use.

Could a system like the ISS be switched to a PSK31 or similar mode in the future?  How well would PSK work with Doppler etc?  I use it on HF, but was wondering if FM and satellites could be feasible.  I believe this was mentioned as possibly being part of Fox's system.

73 Greg N3MVF

My pet hate is AX.25 1200bps FM [on] satellites... ...But the reason AX.25 1200bps FM is still used for new satellites is because there's so much infrastructure, TNC's, PC software etc, already inplace, it's the easy option.

Actually, there is another very important reason. Link budget.

With AX.25 one can have a 2W transmitter on a cubesat which has enough power to hit an HT on the ground with a whip antenna. The same cubesat running BPSK might be restricted to only 200mw.

The difference is the Duty Cycle. The AX.25 packet only lasts 1 second say once every 10 seconds for an average power of 200mw. Which is the same power as the continuous power of the BPSK (200 mw) which is all there is available from the cubesat bus.

But the advantage of the AX.25 BURST mode is 10 TIMEs the RF power to the user on the ground.

For FM mobile-to-mobile satellite communications on OMNI antennas, that is why we use AX.25, to extend satellite links to mobiles.

There are of course other issues and BPSK does have better performance for the SAME power, but as you say, there are not that many mobiles with SSB and all the hardware necessary to auto-tune the radio to track the Doppler.

Bob, Wb4APR

A packet satellite can also be operated simplex (TX and RX on the same frequency). That means a single antenna and no diplexer for both the bird and ground station equipment. On Tue, Jun 7, 2011 at 10:16 AM, Trevor . m5aka@yahoo.co.uk wrote:

Hi Bob,

I accept what you are saying about burst mode but it's possible to develop a BPSK system that does burst mode too.

A BPSK system with Forward Error Correction can offer a 16 dB advantage over AX.25 1200 FM.

As you say there's loads of FM rigs out there so receiving AX.25 is simple and that's the reason everyone still uses it but for the future we should be looking to more efficient means of communication.

73 Trevor M5AKA

--- On Tue, 7/6/11, Bob Bruninga bruninga@usna.edu wrote:

...

...

My pet hate is AX.25 1200bps FM

[on] satellites...

...

...But the reason AX.25 1200bps FM is still used for new satellites is because there's so much infrastructure, TNC's, PC software etc, already inplace, it's the easy option.

Actually, there is another very important reason. Link budget.

With AX.25 one can have a 2W transmitter on a cubesat which has enough power to hit an HT on the ground with a whip antenna. The same cubesat running BPSK might be restricted to only 200mw.

The difference is the Duty Cycle. The AX.25 packet only lasts 1 second say once every 10 seconds for an average power of 200mw. Which is the same power as the continuous power of the BPSK (200 mw) which is all there is available from the cubesat bus.

But the advantage of the AX.25 BURST mode is 10 TIMEs the RF power to the user on the ground.

For FM mobile-to-mobile satellite communications on OMNI antennas, that is why we use AX.25, to extend satellite links to mobiles.

There are of course other issues and BPSK does have better performance for the SAME power, but as you say, there are not that many mobiles with SSB and all the hardware necessary to auto-tune the radio to track the Doppler.

Bob, Wb4APR

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Guess I learned the ITU version :-)

http://en.wikipedia.org/wiki/Simplex_communication

On Tuesday, June 7, 2011, Nigel Gunn G8IFF/W8IFF nigel@ngunn.net wrote:

That's half duplex, not simplex.

On 07-Jun-11 14:55, Justin Pinnix wrote:

A packet satellite can also be operated simplex (TX and RX on the same frequency).