There are currently many single-chip transceivers on the market for IoT applications that are capable of transmitting data over considerable distances at a speed sufficient to transmit audio, such as the Semtech SX1280 transceivers.
Using such transceivers to link repeaters looks more economical and reliable compared to Wi-Fi. This solution has limitations compared to SIP / IAX2, since these transceivers transmit data in simplex mode, but in most cases it is enough to transmit audio from one node to another, in one direction at one time.
The problem is to get the audio stream and telemetry on node A and send them to RS232, and on node B get this data on RS232 and inject it as if it came via IAX2.
The simplest solution seems to be to use the USRP interface and direct the audio stream from UDP to RS232 and vice versa. But in this way it is impossible to transmit telemetry and therefore connect satellite receivers to the voter, for example.
Does anyone have any idea what could be the solution to this problem? It seems to me that the ability to link nodes using such data channels is an extremely important feature that can greatly increase the flexibility of deploying systems consisting of several nodes.
They likely tx in the ham bands if that matters. 430 800 1.2ghz 2.4ghz. /ISM
So, distance can be questionable because of other ‘JUNK’ also there. Mostly at 2.4g.
And to meet FCC requirements, they would be 100mw or less. But the problem is hearing them over floor noise. And there is plenty in 2.4ghz, like your neighbor’s microwave. (yes they leak a little)
But are you sure the data rate is high enough on what you are looking at ?
I suspect these single chip TX’rs are well below 256kbs, but I could be wrong.
And I don’t know how much is needed with some of the lower quality codec’s
I think a method of putting a pure IAX2 data stream on it could work minus the bitrate.
And you have the overhead of error correction to deal with. Hopefully that is a built-in function. Especially at long distance and hostile environments. Likely you need at least 3 times the kbs speed of getting just an audio stream to keep a buffer full.
Asterisk does not like delay.
I would say you are likely better off with some other method. Even an esp32… you can get a breakout board for them that includes the micro ant jack. it’s all cheap.
or I use 5ghz 300mb panel wifi tx’rs. on NATed network. They work well. Get a pair on ebay for under $120,.used micro PC’s are plentiful and cheap. I have tried many things over the years and found it’s just best to stay IP encapsulated. More reliable, simple and modular,
Don’t let me discourage you. I have not seen the radio’s in question so I don’t really know anything.
Just food for thought if you have not thought to hard…
The best stuff comes from those who sit down and hammer it out one issue at a time.
I was talking about the use of a specific transceiver - Semtech SX1280 which, in the FLRC mode, which provides for a certain resistance to interference, provides simplex data transmission in the 2.4 GHz band with a signal bandwidth from 0.3 to 1.2 MHz with a data rates from 260 kb/s to 1.3 mb/s. In this mode, the transceiver uses GMSK modulation, supports strong FEC and interleaving. Also, at data rates up to 256 kbps, interference-resistant LoRa modulation can be used.
It seems to me that under certain conditions the use of such transceivers is preferable to Wi-Fi, which is much more susceptible to interference and has a much lower link budget.
It is possible to organize data transmission over IP, through these transceivers, but such a solution implies increased requirements for the bandwidth of the data channel because of two way nature of communication and higher level protocols overhead. It would be much better to use a special channel driver, like chan_usrp or dahdy_pseudo, to route audio and telemetry packets, including the data necessary for the operation of a simple voter, to the rs232 port to which such a transceiver is connected in KISS mode , stream them in simplex mode to a remote node and inject them in app_rpt for further processing. Such a solution will allow to exclude the excessive overhead.
Basicly we are talking about linking of two nodes on a principle similar to over the air linking by using two simplex analog radios, but in a digital mode that allows you to transmit not only audio but also telemetry, which is primarily necessary for a simple voter functionality.
Also, by supplementing these transcievers with auxiliary hardware, it is possible to run long range data links in the 23 cm band.
While I could be wrong, on the surface, that model looks like they are designed to be designed for short range IoT devices given you use them at any descent bandwidth. Within those parameters, I can see the claim of long range. But that range likely is well under 100 ft. Like a bluetooth device range. Since that is in essence what they are. A bluetooth TX’r.
You can’t cancel out noise that is at the floor of a wide weak signal. Some do slightly better than others based on rx’r quality against internal artifacts. The further the distance, the more noise/potential interference you hear and less of the intended signal.
But I hope you can make that work as you intend. Looks like a lot of work.
Every time I found myself in need, I ended up turning to 5ghz wifi (for low man made interference and high speed 300mb) and with a panel antenna mounted at the focal point of a old satellite dish, 2 of these pointed at each other will go over 5 miles with ease at that high speed. There are some that have mountain top systems say they use them that way for more than 10 miles. Or uhf/430mhz 9600baud digital radios for the cheap low speed side of it (available on ebay for the last decade+) and they tx in the ham bands. But 50/100mw on average but work well on a small yagi on both ends. Use 2/4 for full duplex.
I believe you can get them for 1.2ghz as well.
But I am always looking for something better. But all of this stuff is much cheaper than it was just 5 years ago.
But there is just to much stuff TXing at 2.4ghz/23cm. And it’s growing everyday.
I can no longer use 2.4ghz ATV because of it. And that is a analog signal.Less critical of it.
Every comcast cable modem has a separate wifi modem the company uses to provide wifi calling for mobile phones and using it’s customers to provide it. So it’s distributed everywhere.(a case can be made here for using ham bands commercially without a license) And the mobile phone that nobody ever turns off the wifi when not in use always searching for a network. Just added floor noise for useful digital communications.
23cm/2.4ghz is just out for me.The problems here are just growing exponentially. Have not been able to use it reliably in any distance for 4 years. Heck, even my washing machine has a built-in bluetooth that I can’t turn off. That’s 2.4ghz. My neighbors cars as well. At least these turn off within a hour when the shut the car off. It has become the CB band of data radio.