Questions tagged [digital-modes]

Transmission of digital signals over Amateur Radio, including modes like PSK-31, RTTY, JT-65, JT-9, etc.

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2answers
431 views

BPSK raw data aquisition with HDSDR and FLDIGI

I was playing with HDSDR+ExtIO and Ettus USRP1 to track a BPSK signal. In the end I successfully heard the signal. But I would like to see the data, I mean the raw data (HEX values). For that I tried ...
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2answers
401 views

Which Digital voice mode?

I am looking to get a handheld radio that does digital. Requirements •The most open-source, tweak-able system that I can mess around with. •The lower end price wise •A system that actually gets ...
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3answers
977 views

Are hashes (such as md5) legal in the US

If I were to implement a remote computer control system using amateur radio, would using hashes (such as md5, sha-*, etc...) for authentication be permissible under the United States rules?
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6answers
4k views

What transfer rates are actually achievable using known digital modes?

I've found all sorts of info concerning digital modes, sound samples, spectrum samples, but nobody ever cites what speed a given digital mode can reach. Could anyone tell me more about that, or point ...
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3answers
178 views

Using two radios for a faster data rate

The maximum data rate on UHF is 56kbaud. This is well over most "high-speed" 9600 baud transmissions. Is it possible to use two receivers at one site, and two transmitters (vice versa when the ...
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4answers
3k views

Requirements for 9600 baud

I want to setup a TCP/IP link between my friends house 7km away from me on 70cm. 1200 Baud is a bit slow, and we are looking into something with a faster data rate. I know normal audio does not ...
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1answer
274 views

Sub-1Ghz radio compatibility

I want to ask something about the compatibility issue of the sub-1Ghz radio. If I am using two different RF chips (such as TI's cc1120 and Silicon Labs' si4432; both have FSK modulation), can they ...
2
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2answers
571 views

Receiving BFSK on Kenwood TS2000 transceiver

I have a digital data signal with frequency in the 434-438 MHz band. The data is BFSK modulated with frequency deviation of 9.6 khz, baud rate of 1200 bps. The bandwidth is 25 Khz. Is there a way I ...
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0answers
1k views

Tips on how to setup a MOTOTRBO XPR-8300 Repeater for DMR Ham operation? [closed]

Goal I am trying to setup an XPR-8300 MotoTRBO repeater ultimately with the goal of joining DMR-MARC. Reasoning My area does not have a repeater that's reachable on handhelds. I got a fairly ...
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1answer
201 views

Why are many FHSS / DSSS transcievers limited to 63 mW?

While researching a DIY digital video streaming solution for an outdoor quad-rotor project, I've noticed that a lot of the popular digital transceivers seem to be limited to 63mW transmit power: http:...
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1answer
174 views

FSK real world application BER

I have designed a receiver for FSK reception in 434 MHz ISM band. For this I used USRP1 and GNU Radio. Now, I would like to measure performances of my receiver. For this purposes I did following: I ...
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1answer
618 views

Receive Data on Specific Frequency

So if I were to build a simple AM radio transmitter just using say, my Arduino, an oscillator, and wire for an antenna (this is all crude I know, but work with me here) and use it to transmit data ...
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2answers
2k views

What rig should I start with when trying to get hands-on experience with Fldigi?

I would like to get hands-on experience with Fldigi. What setup is recommendable?
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1answer
73 views

How do I integrate XStream RF modules with any microcomputer (Rasp Pi, Beaglebone)?

I have selected XStream RF modules due to their price and their range (7 miles). I am part of a car team and hence need to transmit and receive data between the car and the ground station (follower);...
3
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0answers
73 views

CML FX919B Forward Error Correcting

I would like to decode de-interleaved demodulated 4FSK symbols that were transmitted using the CML FX919B chip. The datasheet only gives the following information: Forward Error Correction In ...
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1answer
298 views

Are there any satellites in UHF that do not use AX.25? Which of them are in working state? Is the communication to them open?

I have a custom digital transceiver and will like to communicate with digital satellites in the UHF band. It might be fun to try different protocols other than commonly used (like AX.25) as well!
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1answer
376 views

AFSK signal will not decode

I'm trying to demodulate an AFSK signal. My device uses 1200 baud rate and 1200/600Hz as mark/space. I tried using almost every software for demodulation, but nothing worked. Most recently, I tried ...
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2answers
766 views

Getting Started with Digital Modes on VHF on Linux

I am interested in learning about digital modes using 2m and Linux. I have a couple of older 2m rigs (HTX-212 and an old Yaesu) with no additional hardware, like a TNC. What current resources exist ...
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3answers
2k views

How to receive a signal from multiple sources simultaneously (helical antenna)

I'm working on a system (theoretical at the moment) whereby I wish to receive data from multiple sources all transmitting at the same time. I've read that a helical antenna is capable of this. I'm ...
4
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1answer
301 views

Asynchronous vs. Synchronous data transmission speed

Humans are asynchronous receivers, they can pick up words at any time, even if spread out, can combine into a sentence. Data rates are as fast as someone can hear/talk/copy code. All of the fast ...
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1answer
2k views

maximum acheivable range on CB radio by ground wave? [duplicate]

I have 10 watt CB radio system & 0.64 lambda monopole antenna , I think it has a 5 dBi gain . what is the maximum acheivable range by ground wave in an urban area ? If I want to increase my ...
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1answer
142 views

Can club stations register callsigns on the D-Star network?

Some of the members at my local radio club are interested in working with D-Star. Since the equipment is very expensive, it was proposed that the club purchase and operate one rig collectively. Is ...
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2answers
2k views

What is a fixed digital message forwarding system?

What is a fixed digital message forwarding system? I noticed this on the lower end of the 222MHz allocation in the US but it's not explained on the band chart:
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4answers
12k views

How can I decode an AFSK 1200 baud audio clip? (ISS)

I'm a new ham. The past few days, I've had a few nearby passes of the International Space Station. As it was going overhead, I managed to record what I believe to be 1200 baud AFSK transmissions from ...
7
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1answer
129 views

Efficient BPSK31 amplification

I'm looking at making a portable system that can transmit BPSK31. I have a limited power budget, so I'm looking at trying to make my final power amplifier as efficient as possible. From my ...
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2answers
1k views

Digital modes on Field Day

My club is considering doing digital modes next year for Field Day. There are a few issues that we are discussing, including: What modes are most commonly used? How many contacts could be made? What ...
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2answers
115 views

LOS One-way radio system, 4km with at least 1000bytes/s

In order to track skydivers/BASE-jumpers with flysight I am looking for a one-way radio system to transmit the location data. System needs the following specifications: ...
3
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2answers
2k views

What makes JT65 preferable for VHF, and JT9 for HF

Are the bands really that different in characteristics where JT65 works better for VHF, and JT9 for HF? The claim comes from the WSJT website: JT65 was designed for EME (“moonbounce”) on the VHF/...
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7answers
4k views

What does sending SK after calling CQ mean?

When I was at a local radio club today, I witnessed a bit unusual response by a station calling CQ using BPSK31, that is to say phase-shift keying, not the regular A1A telegraphy, on the 20 meter band....
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1answer
1k views

How to calculate UMTS bitrates?

Assuming: Radio frame Subdivided in 15 slots Number of chips: 38.400 Duration: 10 ms; each slots = 666.6 μs and has 2.560 chips Example of channels DPDCH (Dedicated Physical Data Channel) (UL) ...
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5answers
2k views

What about the digital mode ROS causes some to consider it spread spectrum?

The FCC disallows amateur spread spectrum communications below 220MHz. At the moment the relatively new digital mode, ROS, is considered, by some, to be spread spectrum. So this mode is getting ...
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2answers
2k views

Is there a disadvantage to using a cheap HT for APRS?

Looking to build a cheap (not even inexpensive, just dirt cheap) APRS beacon transmitter. Right now you can get a dual band handheld transceiver with rechargeable battery, antenna, etc for under $31 [...
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2answers
731 views

Can an amateur use cellular technologies with SDR?

Software Defined Radio is opening up many new possibilities for amateur digital modes. One family of technologies that interests me is cellular. 2G GSM voice/sms and 2.5G GPRS data has been proven to ...
6
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2answers
507 views

Is it possible for an amateur to transmit ATSC?

Amateur television has long used the NTSC (analog) television standards to transmit video and audio. Several years ago, the digital broadcast television transition made higher-quality television ...
13
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3answers
666 views

What is the role of digital data modes in emergency communications?

Emergency operations are typically reliant on voice traffic today. Are digital data modes used at all in emergency operations, and why/ why not? Couldn't data modes be used to pass information more ...
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1answer
412 views

What is the difference between MFSK64 and MFSK64L?

I noticed this after updating fldigi to decode a Voice of America Radiogram. The only thing I could find in the fldigi changelog was this: ...
4
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1answer
857 views

How can I generate a list of APRS IGates on 30m?

I am investigating using a Tiny Trak 4 with my portable HF radio to self-spot on SOTA activations via APRS on 30m. I usually self-spot via a text message. When I don't have any cell coverage, I can ...
7
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3answers
937 views

Store-and-forward capable satellites in operation?

The amateur satellite community used to have a small fleet of pacsat satellites (AO-16 and friends), which were capable of store-and-forward message passing: you could upload messages to the LEO ...
9
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1answer
2k views

Digital-mode signal reports

When operating analog voice, we give a qualitative (or possibly just arbitrary) signal report, 'scoring' the signal either out of a maximum 'five by five', or a maximum '599'. How do you report the ...
9
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4answers
16k views

2m or 70cm FM mobile radio for digital mode operation

Are there any 2m and/or 440cm FM mobile radios that have audio inputs for supporting digital modes, like PSK31 or SSTV? I have a Rigblaster that I use with my HF radio so I could get a mike cable and ...
12
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4answers
1k views

What is generally considered "too much" power for JT-65 on HF?

Recently, I have begun experimenting with JT-65A, mostly on 20 meters. I usually run about 5 watts with that mode, since I know that JT-65 is a weak-signal mode. Is that still too much power? What is ...
5
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1answer
196 views

APRS: WIDEn-N vs. TRACEn-N

The suggested APRS digipeater path is WIDE1-1,WIDE2-1 for the most use cases. According to the specs, this ensures two retransmissions by fill-in / regular ...
12
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1answer
5k views

How do I discover APRS coverage?

I'm considering adding simple APRS transmitters to my vehicles. I'd rather just put one in and forget about it, but I understand there are areas of the US where a stronger transmitter would be ...
4
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2answers
384 views

AX.25 to Kenwood $PKWDWPL sentence

In my vehicle, I have a Byonics TinyTrac4 paired with an AvMap G6. I also have a Kenwood TM-D710 that I'm currently using for voice. I live in a region of the US where both 2m APRS and 70cm High Speed ...
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3answers
481 views

What's the purpose of a soundcard in digital communication?

If I get involved in digital communications do I need to buy a soundcard? If so, why, what does it do?
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2answers
3k views

HF Digital Mode Band Plan for the USA

I recently started playing with the digital modes, but have been frustrated with the difficulty in finding where certain modes are commonly used. Is there a digital mode band plan for the HF bands, to ...

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