January 2014 - AMSAT-BB - mailman.amsat.org

AO-73 Doppler shift
by Peter Wilson 11 Jan '14

11 Jan '14

Hi all, I'm having great fun on all the operational satellites, including AO-73. However, I find that even using CAT control I have to adjust the uplink frequency almost constantly throughout the pass. I have to shift buy about 3500Hz overall from start to finish, increasing all the time. Is everyone else seeing the same effect? Peter G8KEK

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Re: antenna help
by Nick Pugh K5QXJ 11 Jan '14

11 Jan '14

Hi Bob By comparing the hot sun to cold sky you can figure out the Ratio of antenna gain to system noise. My system noise is undetermined I suspect that my antenna are under performing by about 5 db and I would like to compare it to somebody else antenna. The solar flux numbers are available at both UHF and VHF nick From: Robert Bruninga [mailto:[email protected]] Sent: Saturday, January 11, 2014 8:10 AM To: Nick Pugh K5QXJ Subject: Re: [amsat-bb] antenna help Is it not possible to simply point at the sun and observe the sun noise as a way to baseline your station performance? I dont remember if this can work on VHF or UHF, but it works for microwave. Maybe some experts know the answer... bob, wb4apr On Sat, Jan 11, 2014 at 5:12 AM, Nick Pugh K5QXJ <quadpugh(a)bellsouth.net> wrote: I am trying to check out my antennas. I am looking for someone on the list that has the ability to measure the incoming receive level of signal on a high gain antenna at UHF/VHF . If you have that ability like a flex 5000 uv or similar please contact me off list Thanks nick Office 337 593 8700 <tel:337%20593%208700> Cell 337 258 2527 <tel:337%20258%202527> Helping UL become a world Class Engineering and Educational School _______________________________________________ Sent via AMSAT-BB(a)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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antenna help
by Nick Pugh K5QXJ 11 Jan '14

11 Jan '14

I am trying to check out my antennas. I am looking for someone on the list that has the ability to measure the incoming receive level of signal on a high gain antenna at UHF/VHF . If you have that ability like a flex 5000 uv or similar please contact me off list Thanks nick Office 337 593 8700 Cell 337 258 2527 Helping UL become a world Class Engineering and Educational School

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Japanese Amateur Radio Satellites Launch Feb/March
by M5AKA 11 Jan '14

11 Jan '14

Japanese Amateur Radio Satellites Launch Feb/March http://amsat-uk.org/2014/01/10/japanese-amateur-radio-satellites-launch-feb… Space Station orbit live on Channel 4 HD TV http://amsat-uk.org/2014/01/11/space-station-orbit-live-on-channel-4-tv-2/ Ham radio CubeSats launched to ISS http://amsat-uk.org/2014/01/09/ham-radio-cubesats-launched-to-iss/ ---- 73 Trevor M5AKA AMSAT-UK website http://amsat-uk.org/ Facebook https://www.facebook.com/pages/AMSAT-UK/208113275898396 Twitter https://twitter.com/AMSAT_UK ----

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Re: DTMF on HF?
by kc6uqh＠cox.net 11 Jan '14

11 Jan '14

Howie, The original Marine selective call used two tones which toggled controlling a mechanical escapement. At the end of each 0-9 digit the hold tone was kept on & a pawl would hold the escapement wheel if a pin was placed for that number in the wheel. The next digit would then be dialed. If it was the correct number the escapement would move around to a fixed contact that would sound a bell. If it was the wrong digit the wheel would return to the start position. This system was used on Marine and land mobile phone systems until the SS revolution in the 70's Art, KC6UQH -----Original Message----- From: amsat-bb-bounces(a)amsat.org [mailto:[email protected]] On Behalf Of Howie DeFelice Sent: Friday, January 10, 2014 12:18 PM To: amsat-bb(a)amsat.org Subject: [amsat-bb] Re: DTMF on HF? Bob, I don't have any experience using DTMF on HF but back in the day before satcom, commercial marine HF SSB coast stations used a dual tone selective calling system made by Lorain Electronics. The encoder used 11 tones, one each for the digits 0-9 and a carrier tone. Each digit was transmitted along with the carrier tone and the difference in frequency was detected to decode the digit. This compensated for small frequency variations. These worked very well. You could probably do a similar thing with a single row or column of DTMF if you didn't need more than 4 digits. Howie AB2S _______________________________________________ Sent via AMSAT-BB(a)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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Fwd: Re: Re: DTMF on HF?
by Joe Leikhim 11 Jan '14

11 Jan '14

True, But fixing on the receive end would be more spectrum efficient. And you need to autotune the suppressed carrier anyway requiring receiver side complexity, so why not give DSP a challenge to do it in the blind? With DSP so readily available, I am surprised doppler correction of voice has not been explored. On 1/11/2014 12:05 AM, kc6uqh(a)cox.net wrote: > Joe, > A -16dB pilot carrier would solve the frequency offset problem. This was a > common solution for Marine shore stations in the last century. > Art, > KC6UQH > > -----Original Message----- > From: amsat-bb-bounces(a)amsat.org [mailto:[email protected]] On > Behalf Of Joe Leikhim > Sent: Friday, January 10, 2014 2:31 PM > To: amsat-bb(a)AMSAT.Org > Subject: [amsat-bb] Re: DTMF on HF? > > Since DTMF has two tones for each number, it would seem possible that you > could have some DSP detect the difference frequency of each pair and then > either adjust its decoders or QSY the receiver's VCO to get a lock. > There are a ton of small development boards like Raspberry PI that have > hardware that might be able to do this. > > Has anybody got the AMSAT-bb daily digest to work through their e-mail > provider other than Gmail? > > -- > Joe Leikhim > > > Leikhim and Associates > > Communications Consultants > > Oviedo, Florida > > JLeikhim(a)Leikhim.com > > 407-982-0446 > > WWW.LEIKHIM.COM > > _______________________________________________ > Sent via AMSAT-BB(a)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 > -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida JLeikhim(a)Leikhim.com 407-982-0446 WWW.LEIKHIM.COM

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Re: DTMF on HF?
by kc6uqh＠cox.net 11 Jan '14

11 Jan '14

Joe, A -16dB pilot carrier would solve the frequency offset problem. This was a common solution for Marine shore stations in the last century. Art, KC6UQH -----Original Message----- From: amsat-bb-bounces(a)amsat.org [mailto:[email protected]] On Behalf Of Joe Leikhim Sent: Friday, January 10, 2014 2:31 PM To: amsat-bb(a)AMSAT.Org Subject: [amsat-bb] Re: DTMF on HF? Since DTMF has two tones for each number, it would seem possible that you could have some DSP detect the difference frequency of each pair and then either adjust its decoders or QSY the receiver's VCO to get a lock. There are a ton of small development boards like Raspberry PI that have hardware that might be able to do this. Has anybody got the AMSAT-bb daily digest to work through their e-mail provider other than Gmail? -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida JLeikhim(a)Leikhim.com 407-982-0446 WWW.LEIKHIM.COM _______________________________________________ Sent via AMSAT-BB(a)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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Re: DTMF on HF?
by Joe Leikhim 10 Jan '14

10 Jan '14

The software could first solve for one pair of tones then another, then add or subtract the offset and choose the pair that has the correct fundamental tones. -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida JLeikhim(a)Leikhim.com 407-982-0446 WWW.LEIKHIM.COM

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Re: DTMF on HF?
by Joe Leikhim 10 Jan '14

10 Jan '14

Since DTMF has two tones for each number, it would seem possible that you could have some DSP detect the difference frequency of each pair and then either adjust its decoders or QSY the receiver's VCO to get a lock. There are a ton of small development boards like Raspberry PI that have hardware that might be able to do this. Has anybody got the AMSAT-bb daily digest to work through their e-mail provider other than Gmail? -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida JLeikhim(a)Leikhim.com 407-982-0446 WWW.LEIKHIM.COM

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SatPC32 - New version
by Peter Wilson 10 Jan '14

10 Jan '14

All, Please note there is a new version (12.8c) of SatPC32 available for download. This version has a number of new features - like attaching the "Countdown" window to the main window. Thanks to everyone for helping me over the past few weeks with a number of topics. I am now fully active on all satellites. Peter G8KEK

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