Receiving signals from noaa weather satellites using malachite sdr

[chapi]

I am trying to receive the noaa’s satellites signals using malachite radio but have no success. I have no problem doing it with a simple radio like a baofeng, but not with the malachite.

I need an sdr because I may change the receiving mode to usb and by doing so eliminate the audio from the signal so I can use my Tdoa equipment to find the satellite direction.

It works good with the weather stations.

Any one has a suggestion how to do it or another idea of how to eliminate the audio from the transmission? Or maybe another sdr?

Thanks.

 

[dlwtrunked]

I am trying to receive the noaa’s satellites signals using malachite radio but have no success. I have no problem doing it with a simple radio like a baofeng, but not with the malachite.

I need an sdr because I may change the receiving mode to usb and by doing so eliminate the audio from the signal so I can use my Tdoa equipment to find the satellite direction.

It works good with the weather stations.

Any one has a suggestion how to do it or another idea of how to eliminate the audio from the transmission? Or maybe another sdr?

Thanks.

Eliminate the audio from the transmission??? NOAA POES (Polar Orbiting Environmental Satellites) transmission are done by "audio" FM modulation. You cannot recieve these properly in single-sideband. Please elaborate on what you are trying to do. I think you may be trying to find the satellite direction and strongly suspect you will not be able to do what you are trying as the FM changes frequency and phase. And why? (Programs show where the satellite are at any time.)

 

[chapi]

It’s obviously can be done, since I’m doing it with the weather radio station (162.55 mhz) in my area.

Instead of receiving it with its fm modulation, I use the ssb modulation on the sdr, so the audio is not heard.

My problem is that I am unable to even receive the noaa signal with the malachite sdr, but I hear it strongly on my baofeng.

I know the direction of the satellite, using this technique for another purpose.

 

[ArloG]

You need to use FM with a 40 kHz bandwidth. A simple V dipole may give you acceptable RF signal.
For weak reception you can squeeze the bandwidth lower to reduce noise, at lower image quality.
The signals are fairly weak so using good coax and perhaps an LNA to boost signal level would help.
AM or SSB will not work. It will give you gray and muddy images at most.
Of course you can't hear audio on weather radio in SSB. The modulation is FM. I just tried in SSB and AM. What a trip! No-go.

 

[chapi]

Thanks ArioG. I don’t want to hear the audio transmitted since it interferes with the TDOA instrument’s audio.

Bottom line: Anyone knows of a good sdr radio which can receive the noaa weather satellite’s signal? A $30 baofeng does it easily and efficiently, but the $500 Malachite DSP2 does not..

 

[ArloG]

I think you better explain. You don't have to hear any audio at all if you don't want to and route it correctly to the decoding software.
How are you currently using it? TDOA?

 

[chapi]

I’ll try to explain.

This is a link which shows how TDOA gadget works:

As can be seen, when the antennas are not at the same distance from the rf source, a sound is heard.

For my project I need to feed this audio to an oscilloscope. If the radio source transmits its own audio like in the case of weather channels or NOAA satellites, this audio interfer with the gadget’s audio and thus distorts the measurements.

I can avoid the problem using a different modulation state in the sdr. When receiving the weather channel for example, I use ssb modulation instead of the fm which the original transmission is in. This way the weather audio is not heard, only the TDOA instrument.

Problem is that I am unable to receive the distanced NOAA’s satellites signal with the DSP2 malachite sdr radio, even though it’s easily being done with a baofeng.

But I am not able to eliminate the NOAA’s strong audio signal with the baofeng, since it’s only mode is fm.

 

[ArloG]

And have you considered that the signal coming down is RHCP?
The RF being circular polarized is designed to cover a wide area.
If you were dealing with the L band signal coming down (requiring a tracking system.....normally with NORAD tle and az/el servos systems).
Understandable.
Guess I don't understand your whole purpose. If notching or bandpassing the specific modulated frequency you need is applicable. I guess.

Learn about signal decoding and how open-weather APT works

open-weather.community

 

[chapi]

I can explain the Whole purpose but it will be long and complicated.

What I need is an sdr radio which is capable of receiving NOAA’s satellite’s signal in any mode (NOAA transmits in fm).

Receiving the NOAA’s signal with an sdr will allow me to eliminate the transmitter Audio by changing the sdr’s mode from fm to usb like I’m doing with the weather channel.

A better way to do it will be by eliminating the satellite’s audio in another method that’s I’m a aware of, and use my baofeng to receive the satellite’s signal.

 

[chapi]

An even better way to get a meaningful measurements will be if I’ll be able to display the carrier wave from a distanced rf source on a scope like described in the following link:

ADS-B SIGNAL ON AN OSCILLOSCOPE

Anyone can guide me on how to get a receiver like in this video: So I'll be able to watch an ADS-B signal on a scope? Also if possible to watch signals from GPS satellites or any other rf source 300 miles far or more with a 10ns accuracy. Thanks.

forums.radioreference.com

 

[merlin]

I can explain the Whole purpose but it will be long and complicated

This is because you are making it complicated. Like forget about your post #10, that is a different animal alltogether.
Now, NOAA APT if FM modulated. the signals are about 137 MHz, not the terrestrial 162 MHz.
The downlink RF is RHCP (right hand circular polarised) this is about the antenna, nothing more.
"ANY" receiver that can receieve a 137 MHz range with a bandpass of 30 MHz and receive wide FM will work for NOAA APT.
Most SDR dongles will do this nicely. The Baofeng is not wide enough for good APT. I don't know if the Malechite will do this, specs say it should. SSB will not work, AM will not work. it must be FM.
Now, about audio out: Filtering must be turned OFF or audio tapped before any deemphisis.
SDR software can toggle filters on or off. Audio output is direct from a receive or the system audio that runs your speakers.
This audio can then be piped into APT decoding software. With SDR, virtual audio cable software can do that.
Of course the sound can be muted and SDR sofware has a scope and waterfall.
Back to the antenna. The better is the quad filler helix. (QFH), Rather expensive if bought but easy enough to fabricate youself.
Mounted just above roof line is best, but seen them work indoors.
Another for outdoors is a 'V' dipole, horizontal, best pointed north and south.
That TDOA gadet is a phased dipole, quite directional meaning hand held and pointed to the satellite. If you know where that is.
The QFH antennas are omnidirectional and easy mounted vertical.

NOAA Satellite Signals With a PVC QFH Antenna and Laptop

NOAA Satellite Signals With a PVC QFH Antenna and Laptop : This instructable covers everything you'll need to get started in being able to receive the APT (Automatic Picture Transmission) signals from the NOAA Satellites (NOAA-15, 18, and 19) flying overhead (and can be a foundation for...

www.instructables.com

 

[chapi]

Thanks Merlin, always good to hear from you.

If you or someone is interested, I’m willing to elaborate, but it’s involves a lot of physics. Interested in quantum and relativity?

What I do not understand is why am I able to get the signal easily in my baofeng but not with the sdr.

A complicated antenna will not do, since if you’ll follow comment 10, you’ll notice that in the project the antenna is rotating rapidly

Bottom line is this: I have everything working properly with the weather channel. I also can use the apparatus and receive distanced stations with my baofeng that transmitting in cw, since the baofeng receives only fm signals and thus eliminates the audio from the signal.

But noaa is perfect for the project because it’s far and strong and there’s hardly multi path interference.

Any suggestions?

 

[merlin]

Well, this is about NOAA LEO satellite reception. As stated ADS-B is a totally different animal and does not apply to APT.
OK, you hear signals with your Baofeng, are you getting good APT decoding with it ? (that is the goal is it not)
Weather channel on 162 MHz is voice only, no wefax or other information. Still, this has nothing to do with APT.
Of the three active NOAA satellites, they each have a discreet downlink frequency. all about 137 MHz.
The only time you get a signal is when the satellite is in range about 10 degrees above your horizon or overhead.
To determine that, you need to watch N2yo.com Or you can use a program like WXTrack.
Here, you can see NOAA 18 in range of my location:
And here on n2yo:

Technical details for satellite NOAA 18

NOAA 18, known before launch as NOAA-N, is a weather forecasting satellite run by NOAA. NOAA-N (18) was launched into a sun-synchronous orbit at an altitude of 854 km above the Earth, with an orbital period of 102 minutes....

www.n2yo.com

 

[chapi]

I know about n2yo.

I will try one more time:

I can listen to weather channel at 162.5 mhz fm with both baofeng and malachite sdr.

I can listen to noaa at 137.2 mhz fm with the baofeng, very strong signal.

I Cannot listen to noaa with the malachite sdr. No reception and no waterfall in any mode.

Why?

Only this please.

 

[Freemor]

WX radio is a strong terestrial signal.
NOAA sats are a non terestrial signal.
I know that for my SDR I needed a 6db LNA to be able to really pull in the NOAA satellites. And that is with a large discone antenna. I could see the signals without the LNA. but I wouldn't have classified them as strong. Perhaps you Boafeng has a built in LNA that your SDR is missing.

Or perhaps you just need to turn the gain on the SDR up more. when trying to listen to the NOAA satellites.

 

[dlwtrunked]

Thanks Merlin, always good to hear from you.

If you or someone is interested, I’m willing to elaborate, but it’s involves a lot of physics. Interested in quantum and relativity?

..

Do not under-estimate some of us. I read in both subjects (general and special relativity since high school and QM for the last couple years with some of my own ideas about QE. Throw in a PhD in mathematics. But I still wonder what you are trying to do and why.
Also, which Baofeng model is it? Also puzzling, NOAA APT sats at 137 MHz are easily heard with a whip antenna. the NOAA satelittes have plenty of power for the clear path to earth. A discone (I do use one for other reception) has no gain and the only advantage to one (other than being broadband) for this is is if you can mount it high to get better reception at the horizon. Something is not right with your setup.

 

[merlin]

I know about n2yo.

I will try one more time:

I can listen to weather channel at 162.5 mhz fm with both baofeng and malachite sdr.

I can listen to noaa at 137.2 mhz fm with the baofeng, very strong signal.

I Cannot listen to noaa with the malachite sdr. No reception and no waterfall in any mode.

Why?

Only this please.

I can only suggest your Malechite lacks the needed sensitivity. I doubt your reception with the Baofeng is 'very strong'
I do somtimes get a signal with my Baofeng, but just manipulating the radio, the signal can be lost.
I get enough signal with a Harris radio and discone to break squelch, but not strong by any means. Might be strong enough for some APT decode, but not expecting a good, noise free image.
Maybe some overlooked setting, I would think even with the whip you would get some indication of a signal.

 

[merlin]

NOAA APT sats at 137 MHz are easily heard with a whip antenna

I'm betting if you re orient that whip, the signal is gone. These sats are just not that powerful.
It took a 15 Db gain preamp with my QFH to get some decent APT.
You need a good 25 Db signal to noise ratio for some good APT.
(Yea, overkill on the preamp, but attenuation makes up for it.)

 

[merlin]

I read in both subjects (general and special relativity since high school and QM

Never been much into QM, really no place for it in my profession.

 

[dlwtrunked]

Never been much into QM, really no place for it in my profession.

I have run into it in regard to Quantum Mechanics and communications but not the stuff most run into regarding radio communications.