Why is antenna Elevation declining?

I’m looking at Inmarsat 4-F3. For many months N2YO.com has shown my location to be about 44 degrees. Now for a few weeks the elevation shows to be about 38 degrees. I know this change is gradual. I just happened to notice it looking at the N2YO website. Azimuth always shows to be about 145 degrees, for the bird is Geostationary.

The answer is easy… You must be living on top of a super volcano, and the ground is rising underneath you… :wink:
Either that r the satellite is falling towards the ground on the horizon LOL
Seriously though, some “geostationary” satellites trace a very slow “figure 8” in the sky over a year or so, so maybe you are seeing that? However that is quite a large change you are seeing, and the elevation of communication satellites does not normally change that much ( otherwise all the dishes would need re-aligning! )
This site shows the rate and direction of position change of the satellite http://www.satellite-calculations.com/Satellite/Catalog/catalogID.php?33278


I asked this question to escape from the many newbie questions of “this works, but why does that not work”. I asked the same questions a number of months ago. But, now I have no problems, until Syed shuts the door on the Raspberry Pi and have to go get a CHIP and ask all new questions!
Anyway, the Elevation question is based on my satellite favorite link here.

At the right you see Elevation at 39.9 degrees. A couple of days ago it was 38. But all spring & summer long, it was always about 44. But it looks like now the Elevation is going back up. I know you’re thinking this is all frivolous and I agree. I guess it’s all about orbit decay. However, the Azimuth is always about the same. All this just an observation. Now back to the Outernet. Sometime in 2017, it will be Showtime! (I hope) :slight_smile:

Happy Holidays to all the Outernet folks, especially the hard working geeks and gurus.


What do you think about an actual radio/audio channel?

I just could help but respond to your post :wink:
I am a “newbie” to the L - band CHIP stuff - I was running stuff about a year & a half ago.
I only set up again with the CHIP an the brilliant patch antenna a couple of days ago, and have been asking the silly questions myself!
I have a great need to understand how everything works, so I will be a nuisance here on the forums for a couple of Months until I am “happy” :slight_smile:
Happy Holidays to you too!

intriguing - :slight_smile:

WOW! … World Wide Outernet DMR ! :grinning:

I was thinking more along the lines of an audio “podcast” that would be produced regularly & HEAVILY compressed for downloading at data rate of the Outernet channel
DMR is really quite bandwidth heavy, and is real BIG pain if any packets are lost. - Unless I am missing something here. Is there more bandwidth available from the satellite?

Another spontaneous outburst from me! Glad Christmas shopping is over. I wasn’t sure what Syed meant when he said a radio/audio channel. I do know DMR uses error correction in both directions. And the audio is very good. I realize now about bandwidth. It’s highly important not to use to much. So, scrap my idea and I’ll try to contribute an idea that’s possible in the future.

I wonder if we receive people can get a status report of the “new” Outernet being brewed? Say every 10 days or sooner. Maybe the report is somewhere, but not sure where to look.

Do you mean DRM; Digital Radio Mondiale?

1 Like

Now that might work. Many years ago I learned about DRM and modified a Kenwood R600 receiver by adding a few parts to bring out a 12 KHz IF. When tuned to the correct SW frequency and piping the output IF into a PC sound card and using licensed Dreams software, I heard great sound. Almost like FM. I played around with DRM for about a year, until the broadcast schedule changed and the Sunspot cycle decreased. The DRM transmitters and antennas really favored Europe and not the US. But, I was able to receive a DRM station on the East coast on the 31 meter band. And even from the Island of Bonaire on 19 meters, At the time DRM was pretty much experimental, transmitting 4 channels of digital on Short Wave. 2 channels were used, one for audio and one for text. The software even decoded the text! I had fun. Not sure if this mode is still being used.

DMR is: Digital mobile radio (DMR) is an open digital mobile radio standard defined in the European Telecommunications Standards Institute. It is used commercially through out the world, and lately by Radio Amateurs.

1 Like

The prospect of transmitting some audio content over Inmarsat is intriguing and could possibly be accomplished, with the assumption that there is significant bandwidth available. DRM would not be efficient unless there were actually a 12kHz analog channel made available. The other constraint is SNR, which can be a challenge without perfect conditions, using the small patch antennas.

Using DReaM (in transmitter mode) or Spark, one can explore the different results from various encoding profiles that are narrower than DRM on HF. It is also possible to send digital audio inside 2.8kHz using something like the Codec 2 that is used with FreeDV http://freedv.org/tiki-index.php This generally provides a low quality voice channel over SSB.

If the hope is to provide anything close to even mono AM broadcast quality, then the bandwidth budget would need to be dramatically increased. Inmarsat provides some voice services at just under 5 kbit/sec, but those are not suitable for anything but phone quality audio.

1 Like

Hi @syed
@donde explains the difference in DRM Vs. DMR but IMHO both are far too bandwidth hungry for “real time” audio
The same goes for the SSB DV.
I think that a “non- real time” regular “podcast” type system would be a better fit, unless you have bandwidth to spare :slight_smile: but what content? there is that “bias” thing again LOL!

BTW, have you see what VOA Radiogram have been doing with the HF and low datarates on AM Sortwave (typically MSFK 32) ?
https://voaradiogram.net It is a bit of fun to Receive, but if HF is ever on the Outernet’s radar, then that is a possible delivery method :slight_smile:

http://www.digidx.uk/ is doing the same thing roughly as the VOA Radiograms. These methods have been under dev for a long time. The low bitrate is actually fine for “reading along” as the transmission comes in, and images don’t take too horribly long to come across.

DRM is indeed still in use in Russia, China, India and the UK an Germany. It is delivered via HF, MW and even VHF using DRM+ Unfortunately, here in the U.S., DRM is mostly not received. There used to be blocks of programming on the Sackville relay, but that’s been gone for a while.

There is also a new portable SDR hitting the market, based on simple inexpensive hardware, and is something that could just as well be receiving Outernet as an ancillary mode for delivering additional content - http://titusradio.com/
All the necessary hardware is there minus the patch antenna.

We do a lot of HF Digital at the K5TED shack :slight_smile:

@k5te - I also do basically HF digital too (M0KNC) including Pskmail (http://pskmail.org/) & winlink fro HF email.
I know DigiDX well, and have corresponded with Stephen in the past. Kt is good to see he will be transmitting in Europe agan this week from the Italian bradcaster. I also correspond with Kim from VOA - he transmitted one of my photo not too long ago in the radiogram too.
The analogue images are always hit & miss, but 99% of the time if there is any signal I can decode 90% of the MSFK from the UK.

I listen to DRM most nights from All India Radio from here on (about) 3900 Khz It has been a project of mine to try to receive it with no dropouts with the SDRplay… I am getting there sloooowly :slight_smile:

BBC gave up on DRM a few years ago…

Isn’t BBC still doing DRM over the Woofferton site?

the last Schedule on the BBC World service site was from Summer 2009 :frowning:
I have never heard them on DRM
It Does look like the DRM website says they broadcast from 0600- 0700 though :slight_smile: I will have to try recodoing that LOL!

@neil, @k5ted

BBC still broadcasts in DRM mode on 3955 kHz via Woofferton (100 kW, 141 deg) and on 5845 kHz via Nankhon Sawan (100 kW, 290 deg), albeit these two frequencies are not mentioned in their current shortwave frequencies web page.

Please see the latest reception reports at http://www.drmrx.org/forum/forumdisplay.php?f=22

Season’s Greetings,

Merkouris, SV2HWM

Thanks @Chorbev
I actually had a listen at 3955 (it seems it is between 0600 & 0700 ) the other day, and there was a signal there but far, far too low in the noise to decode.
It would be interested to know when it is broadcast on 5845, as I would have better luck there…
there seems to be no info on it… I know that the BBC announced that the DRM would stop waaaay back in 2010, but it seems they have been doing it anyway LOL!