5 ms·

When the limit was put in place, we didn't know that symbol rate and baud rate could be different. A lot of these discoveries really came into their own during

When the limit was put in place, we didn't know that symbol rate and baud rate could be different. A lot of these discoveries really came into their own during the 90's and enabled far more data transmission than previously imagined. However, amateur radio has some natural conservatism to it, like Morse code requirements (since retired) to gatekeep the hobby. Getting rid of this baud rate limit is long overdue as analog transmissions are laughably archaic for anything outside amateur radio.

thrtythreeforty 3y ago
Do you mean bit rate and baud rate can be different? My understanding is that baud rate and symbol rate are the same thing.
- fsckboy 3y ago
  if there are two possible symbols in your communication medium that you switch between, bit rate is baud rate (with the two symbols being 0 and 1). If you have more symbols, then baud/symbol rate increases will correspond to greater bitrates increases by a factor.
  - Steltek 3y ago
    Okay, I was pretty sure I had it right the first time but my confidence is rather low since it's been a while since I read up on it.
- Steltek 3y ago
  Oops, yeah and it's not quite my domain of expertise. In fact, that's the big draw for me: Amateur radio has been amazing for filling in knowledge gaps of low level electrical engineering details. it takes things way past the simple CPU/system models from university CS class and the Arduino DC logic hobby projects. The educational potential is really top notch.
- mal10c 3y ago
  Baud rate and symbol rate often refer to the same thing, especially in the context of digital communications. However, they don't necessarily equate to the bit rate. In the digital realm, we're familiar with the concept of 1's and 0's, which represent binary states. When we transmit a single bit, it can be visualized as a digital line being high (for 1) or low (for 0). The rate at which this line transitions from one state to another is called the baud rate or symbol rate. To understand this further, let's consider a more advanced modulation scheme. Instead of just having two states (high and low) to represent binary bits, imagine we have four distinct states: high, medium-high, medium-low, and low. These states can represent combinations of bits as follows: high = 11, medium-high = 10, medium-low = 01, and low = 00. In this scenario, each state transition represents a symbol, and since each symbol can represent two bits, the symbol rate (or baud rate) is half of the bit rate. If you know the symbol rate and want to determine the bit rate, you'd multiply the symbol rate by the number of bits per symbol. In this example, you'd multiply the baud rate by two. Most signals rely on techniques beyond simple voltage differences though to transfer information, and that's when you delve into the world of RF theory. Instead of a discrete voltage, a sine wave is used at a particular frequency. The amplitude of the sine wave can be adjusted just like we adjusted the voltage on that line. If we want even more symbols, maybe 0000 to 1111 or bigger, we can introduce another variation to the sine wave called phase. Phase of a sine wave is just shifting it left or right, but could be visualized as two people on a race track. If they start a race from the same line and run at the same speed in the same direction, they're in phase. If one of them starts a quarter of the way ahead from the other and they both run at the same speed in the same direction, then he's a quarter phase shifted from the other. That adjustment of phase and amplitude falls into a broad category of RF modulation called QAM, and it's used in more than RF between two radios. It can also be used over Ethernet or PCIe busses. I could go on rambling for a long time on all this, but hopefully this helps answer your question.
selfhoster11 3y ago
Morse sounds like a useful thing, really. There aren't many digital encodings that can be done by hand and still remain readable in high-noise conditions.
- vvanders 3y ago
  Oh it's useful and if you want to use it that doesn't change. However a number of us are interested in the digital and experimental side of ham radio, for that morse code doesn't really offer anything and it's a non-trivial hurdle to cross. The hobby already struggles with gatekeeping/driving off people who don't "ham right" and so making the hobby more accessible is a big positive in my book.
  - lostapathy 3y ago
    Exactly this. Current ham regs in the digital modes really, really limits what you can do, and keeps it in the dark ages compared to what goes on in 900mhz and 2.4ghz with unlicensed devices. We need to get back to where having a ham license means you can do cutting edge things!
  - kmbfjr 3y ago
    Give it a rest. No one holds you back in amateur radio and if the comments of old farts bothers you, perhaps you need to evaluate what prompts them to tell you that. As long as you are Part 97 compliant, what exactly is your problem?
    - vvanders 3y ago
      Thanks for confirming that attitude still exists :)
- adgjlsfhk1 3y ago
  it has a number of pretty big downsides. for example, it's not a hamming code and isn't self synchronizing. it's not horrible, but it is missing a lot of the properties you would want from a modern digital code.
Crunchified 3y ago
Plenty of stories of old hams that became dysphagic following a stroke, but could still chat with fellow hams using Morse - whether using simple finger movements in the hospital or months later on-the-air.
kmbfjr 3y ago
It has nothing to do with amateur radio operators being conservative. The rules were what they were, and amateurs experimented within those rules such as modifying fax modems for use on HF. The FCC set the rules, not a bunch of old farts upset that the morse code test was eliminated. But because the FCC doesn’t pay much attention to the Part 97 service, it has taken them this long to get around to updating the rules. This change was proffered as far back as 2008 at a Dayton TAPR session.
deleted 3y ago
[deleted]

thrtythreeforty 3y ago

Do you mean bit rate and baud rate can be different? My understanding is that baud rate and symbol rate are the same thing.

fsckboy 3y ago
if there are two possible symbols in your communication medium that you switch between, bit rate is baud rate (with the two symbols being 0 and 1). If you have more symbols, then baud/symbol rate increases will correspond to greater bitrates increases by a factor.
- Steltek 3y ago
  Okay, I was pretty sure I had it right the first time but my confidence is rather low since it's been a while since I read up on it.
Steltek 3y ago
Oops, yeah and it's not quite my domain of expertise. In fact, that's the big draw for me: Amateur radio has been amazing for filling in knowledge gaps of low level electrical engineering details. it takes things way past the simple CPU/system models from university CS class and the Arduino DC logic hobby projects. The educational potential is really top notch.
mal10c 3y ago
Baud rate and symbol rate often refer to the same thing, especially in the context of digital communications. However, they don't necessarily equate to the bit rate. In the digital realm, we're familiar with the concept of 1's and 0's, which represent binary states. When we transmit a single bit, it can be visualized as a digital line being high (for 1) or low (for 0). The rate at which this line transitions from one state to another is called the baud rate or symbol rate. To understand this further, let's consider a more advanced modulation scheme. Instead of just having two states (high and low) to represent binary bits, imagine we have four distinct states: high, medium-high, medium-low, and low. These states can represent combinations of bits as follows: high = 11, medium-high = 10, medium-low = 01, and low = 00. In this scenario, each state transition represents a symbol, and since each symbol can represent two bits, the symbol rate (or baud rate) is half of the bit rate. If you know the symbol rate and want to determine the bit rate, you'd multiply the symbol rate by the number of bits per symbol. In this example, you'd multiply the baud rate by two. Most signals rely on techniques beyond simple voltage differences though to transfer information, and that's when you delve into the world of RF theory. Instead of a discrete voltage, a sine wave is used at a particular frequency. The amplitude of the sine wave can be adjusted just like we adjusted the voltage on that line. If we want even more symbols, maybe 0000 to 1111 or bigger, we can introduce another variation to the sine wave called phase. Phase of a sine wave is just shifting it left or right, but could be visualized as two people on a race track. If they start a race from the same line and run at the same speed in the same direction, they're in phase. If one of them starts a quarter of the way ahead from the other and they both run at the same speed in the same direction, then he's a quarter phase shifted from the other. That adjustment of phase and amplitude falls into a broad category of RF modulation called QAM, and it's used in more than RF between two radios. It can also be used over Ethernet or PCIe busses. I could go on rambling for a long time on all this, but hopefully this helps answer your question.

selfhoster11 3y ago

Morse sounds like a useful thing, really. There aren't many digital encodings that can be done by hand and still remain readable in high-noise conditions.

vvanders 3y ago
Oh it's useful and if you want to use it that doesn't change. However a number of us are interested in the digital and experimental side of ham radio, for that morse code doesn't really offer anything and it's a non-trivial hurdle to cross. The hobby already struggles with gatekeeping/driving off people who don't "ham right" and so making the hobby more accessible is a big positive in my book.
- lostapathy 3y ago
  Exactly this. Current ham regs in the digital modes really, really limits what you can do, and keeps it in the dark ages compared to what goes on in 900mhz and 2.4ghz with unlicensed devices. We need to get back to where having a ham license means you can do cutting edge things!
- kmbfjr 3y ago
  Give it a rest. No one holds you back in amateur radio and if the comments of old farts bothers you, perhaps you need to evaluate what prompts them to tell you that. As long as you are Part 97 compliant, what exactly is your problem?
  - vvanders 3y ago
    Thanks for confirming that attitude still exists :)
adgjlsfhk1 3y ago
it has a number of pretty big downsides. for example, it's not a hamming code and isn't self synchronizing. it's not horrible, but it is missing a lot of the properties you would want from a modern digital code.

Crunchified 3y ago

Plenty of stories of old hams that became dysphagic following a stroke, but could still chat with fellow hams using Morse - whether using simple finger movements in the hospital or months later on-the-air.

kmbfjr 3y ago

It has nothing to do with amateur radio operators being conservative. The rules were what they were, and amateurs experimented within those rules such as modifying fax modems for use on HF. The FCC set the rules, not a bunch of old farts upset that the morse code test was eliminated. But because the FCC doesn’t pay much attention to the Part 97 service, it has taken them this long to get around to updating the rules. This change was proffered as far back as 2008 at a Dayton TAPR session.

deleted 3y ago

[deleted]