Communicating Wireless With Two Transceivers (Satellite Communication)

Hi,

I am working on a project that has something to do with satellite communication (CubeSat). I was tasked to purchase two commercial off the shelf transceivers (Alinco DJ-S45E & Alinco DJ-C7). The DJ-S45E is to be connected to a function generator to simulate data to be transmitted. And the DJ-C7 is to be connected to a oscilloscope to make analyze the received data. As such, what i mean is that I am using the DJ-S45E to transmit wirelessly to the DJ-C7.

First I tested over a wired link. What I mean is that I connected a wire connecting both the transceivers' antenna port. After which I tried to transmit, and I got the desired data I wanted.

But the problem I am facing now is that I am not able to get/receive the actual data that I am suppose to get when I am doing it wirelessly. I am really unsure of what is the problem of how is it not able to communication wireless.

Anyone who have encounter a similar problem or may have a solution to it? Thanks a lot.

Regards

To replace "a wire" for wireless communication, you must connect suitable antennas to both transceivers. Antennas make sure the transmitted energy is converted into the electromagnetic wave, at the receiving end, converted back to moving charges in antenna line in your transceiver.
There is no wireless communication without antennas.

I do not know the specifications of your transceivers but it may be time to read them and the instruction for use.

There is a Cubesat forum (see the links)
1) **broken link removed**
2) **broken link removed**

If you ask the same question there maybe somebody who encountered same problems as you will give you a helpful answer.

Wql said:

Hi,
First I tested over a wired link. What I mean is that I connected a wire connecting both the transceivers' antenna port. After which I tried to transmit, and I got the desired data I wanted.
But the problem I am facing now is that I am not able to get/receive the actual data that I am suppose to get when I am doing it wirelessly. I am really unsure of what is the problem of how is it not able to communication wireless.
Regards

Click to expand...

Well if you directly connected the 2 antenna ports and then transmitted on the Alinco DJ-S45E. I can tell you what the problem would most likely be ..... you have killed the receiver by pumping a heck of a lot of RF straight into a sensitive receiver!!!! it would have totally fried the receiver circuitry..... time to buy a new DJ-C7 !!!

Dave

Yep, you probably sent 1 to 10 watts of power into a receiver expecting nanowatts of power to be received.

There is a small chance that the receiver had a limiter at its front end and it protected it.

Also, we are assuming that your satellite transceivers were "complete"...that is that they contained the RF componentry to attach directly to an antenna. Sometimes the satellite transceivers have 2 boxes each--an indoor and an outdoor unit. The outdoor unit would turn the lower frequencies into the microwaves that the antenna would work with. Assuming you knew that, and have the right type of hardware to hook up to a coaxial cable, you will need something like a 90 dB attenuator pad between transceiver one and transceiver two.

Hey Biff

these radios he used were just standard amateur (Ham) band radios dual band VHF/UHF nothing special

I cringe when I hear some of the things that ppl do to good pieces of gear

Dave

Hi guys,

thanks for the reply. I didn't know that by connecting the antenna ports directly will have such effects. luckily i still got spare transceivers. okay, the next time I will just do the testing with the antennas attached. Thanks again for ur advice.

Hi again,

I just did a retest using the "supposed damaged" DJ-C7 to receive voice from my brand new set of DJ-S45. And it was able to receive the voice through wireless channel. So I am wondering if this is counted as "still working" or maybe there are other parts that are damaged? Thanks again everyone.

Regards

Hi again,

Just want to ask something. If lets say I don't disassemble the transceiver, and try to connect the signal generator's signal to the external microphone's input hole of the transceiver input using a 2.5mm mono plug jack cable. Is there going to be any problem arising from this type of connection? And one more question, normally the signal's amplitude must be set to which range so as to not damage the transceiver?

Thanks.

Regards

1) Buy a (cheap) microphone with a jack connector. One time I bought one with less than two dollars.
2) Connect the oscilloscope ground clip to the top, inner contact and put the probe on the bottom, outer contact of the jack.
3) Whistle in the microphone, preferably a musicale note (a continuous tone), and watch the oscilloscope display. The amplitude of the signal generated by your function generator should by no greater than the magnitude of the signal generated by the microphone.

P.S.
I have a bad feeling that something wrong happened to your first DJ-S45E and now you try to connect the signal generator to the external microphone female jack port of a new DJ-S45E.

My advice is to first download a Tone Generator and a Software Oscilloscope from the internet and to follow the scheme below:

PC+Tone Generator Software -> SoundCard -> Loudspeakers -> Transceiver -> Antenna -> ....... WirelessLink ......
...... Antenna -> Trancceiver -> Microphone -> Sound Card -> PC+Software Oscilloscope

You need just one sound card, one computer for both sound generation and sound visualization.

The tone generated by your computer will be transmitted in the PC loudspeakers from there to the DJ-S45E own microphone which will transmit wirelessly the signal to DJ-C7 whose own loudspeaker will send the sound to a computer microphone connected to the sound card and finally the sound will reach your Software Oscilloscope.

Doing like this you do not risk anything because you do not electrically touch any of the two transceivers.

Hi tempos, thanks for ur advice. I think I will first get the microphone with a jack connector, den plug into the female MIC connector and measure the amplitude from there.

And is there any software oscilloscope u can recommend? Thanks thanks.

is there any software oscilloscope u can recommend? Thanks thanks.

Click to expand...

See **broken link removed**.

Okay thanks! I will try to use this method.