[OT] Analog amplifier to EEE PC 901

The items for sale, are delightfully free of specs.

Some applications will work better than others. The higher the quality of vinyl recording player, the less likely one of these cheap gadgets has sufficient gain for the job. (This is because inside one of those, is a single chip, and little else. The gain, is whatever the main chip can manage, and it was never designed for magnetic cartridges. A purpose built device, would have a gain stage in front of the chip.)

Excess capability in devices is nice for "research" purposes. My paper scanner may record at 1200 DPI, but I never scan over 300 DPI. But when I want to investigate what someone has been telling me (that higher DPI doesn't help overall), then my equipment is up to the task of running at a higher rate to prove or disprove the theory.

My first paper scanner, came with slide templates and a transparency adapter. But the people were out of their freaking minds. The scanned slides were as grainy as hell (not the right sampling rate). I wasn't expecting miracles -- I was impressed by their negative compensation, the colours on some negative scans were good. But the ugly results were not keepers. At least the scanner could display the "principles" of scanning film, but it could not actually realize useful output while doing so. This is why we have those shoebox shaped film scanners.

In this example, are some specs. A start at it. This is how we bootstrap into being forewarned.

Now we can look up all the missing specs.

It has an internal regulator for the analog supply voltage. Dirty 5V from USB bus, clean 3.3V, but as it turns out, there are better ways to make a clean 3.3V than that, and if you want an exceptional noise floor, you'll need a buck converter and a couple stages of analog supply filtering to notch the fundamental. Even a battery has a noise spectrum, so you can't necessarily get a better result with just a battery.

Since it is USB, you wold never really expect a good noise floor, but... if someone does the work, who knows what you could manage. One of the problems fifteen years ago with computer audio, is the engineers weren't running RightMark to see how good their workmanship was ("mouse noise injected into audio recording"). They had no clue what the actual specs were for their audio. But they listened to the feedback, and corrected the situation (there are still occasional slip-ups, moat is missing).

Paul

I didn't ask you and WiFi transmit Digital. How it is done is not the point, it is digital.

The carrier wave is analog. The modulated data info is digital.

On Sun, 11 May 2025 21:42:25 +0200, Edmund snipped-for-privacy@hotmail.com wrote in <vvquj1$k07g$ snipped-for-privacy@dont-email.me:

Why are you being rude? He posted that to help you understand.

Yeah I see it, it doesn't sound friendly, but it was not intended to be rude and especially not towards someone as helpful as Paul. I just wanted the source of The Natural Philosopher for his claims. Sorry Paul!

It is parsed by humans as being digital. It is conceptually digital. Nothing is truly digital until you are working at atomic level or with individual photons. The digital signal will have threshold levels specified for correct interpretation of 0s and 1s, and a maximum timing jitter specified. All those things are analogue values.

I once had to fix a problem in a TV digital effects unit, which turned out to be an IC having been sourced from the wrong manufacturer. It had an (unspecified) input impedance which was too far mismatched from the PCB lines feeding it, resulting in a huge reflection that messed up the timing of the 'digital' pulses. That's an analogue problem.

Rather than analog and digital, everything is analog, and we choose to apply a "digital-overlay" or a digital interpretation to the things we are seeing.

On this page, you can see some almost-ideal behaviors, and the "digital-overlay" is easy to justify when you look at the results. This isn't the first logic family, but it's one of the cleanest.

Now, let's do a 4096 I-Q constellation. Is it still digital, or is it looking just a wee bit analog ? At one time, they were not going to do

No s*it.

Those dots are decision points. The signal does not need very much low speed wander, for the voltage value to move from one decision point to another, then you get a receive error. And if you are lucky, an error correction mechanism can fix it for you.

If you looked at that signal in the time domain, it would look just awful. There's a reason the instruments put up the constellation display, rather than the oscilloscope type display.

OK, this is the oscilloscope display of a low-QAM (Quadrature Amplitude Modulation) signal. Can you extract the ones and zeros from this correctly ? Now, let us connect the instrument to the 4096 constellation, and you get your pencil out and try that one. Good luck with that.

There are actually a lot of PHYs now, where your "calibrated eyeball" is useless.

The first time I looked at LVDS on a scope at 622, I thought it was snowing. Yet the chippage received the signal perfectly. The rep and I had a good laugh, about what we were seeing on the screen, and the inability of humans to recognize a good time. So yes, that was digital, because our data was coming in, error free. All I really needed was a better trigger, to make the display usable. I think later on, I got one of those properly triggered, and it still bobbed around a bit on the screen. But at least it was looking a bit more trapezoidal then.

Well that sums it up I guess, so WiFi IS digital, that is the whole point here.

To me, wifi is 'radio' which is analog. Radio is modulated in various ways for various purposes and it is but a small part of a huge electromagnetic spectrum which is analog.

How you put the data into some part of the electromagnetic spectrum depends on whether you are trying to communicate to other parts of the solar system or nearby.

You can find black white but that doesn't make it so.

All the transfered WiFi data is digital that is why we call it digital. making this an endless war of words, fine I don't care.

In these types of discussion, I'm not trying to say you are 'wrong' about how you want to think about it, but I'm explaining how I think about it and how I see it.

The analog is 'fundamental' mechanism to wifi radio, the digital data is 'tacked onto' it.

You basically have transmitter and receiver radios and an appropriate frequency. Whatever else you have/do is another 'subject'.

Wifi and cellphones use DSP to convert digital data into radio waves by modulation, while radio/TV (usually) don't.

Modulating a radio wave doesn't make it 'not a radio wave'.

Indeed. The Panasonic RX-ES27 Radio/CD/tape recorder/player that was bought for Dads 80th birthday in 2003 is now with me but he never played cassettes and the spindle that the pinchwheel compresses the tape into had developed some rust. I have cleaned it off with some fine wet'n'dry cloth and am contemplating sleeving it with a short length of heat shrink tubing. This might protect any tapes but they would play slightly faster. For speech (mostly old language cassettes and stuff like Tony Hancock or "I'm sorry I haven't a clue") this may not matter.

It's a good system, and ebay prices seem to vary between £40 and £100. It was £120 new in 2003. It has a remote control and a servo-controlled tape deck so you can Fast Fwd and Reverse without getting up to press clunky buttons.

Its radio innit.

"Basic Modulation Types

WiFi technology uses several modulation types, including Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), and higher-order QAM. BPSK and QPSK are relatively simple, offering robustness at the expense of data rates. QAM, on the other hand, offers higher data rates but is more prone to noise. Advanced Modulation Techniques

More advanced WiFi standards, such as 802.11n (WiFi 4), 802.11ac (WiFi

In QAM, the WiFi signal changes both its phase (like turning around at different points while walking) and its amplitude (like changing the volume of your voice). These two changes happen at the same time, which is like singing a song while dancing; you're doing two things at once! The number before QAM (like 64 in 64-QAM) tells you how many different combinations of amplitude and phase changes you can make. In our dance-and-sing analogy, a higher number would mean you have more dance steps and song notes to combine.

How Speed Depends on Modulation

Bits per Symbol and Data Rate

The choice of modulation directly impacts the WiFi speed because different modulations can transmit different amounts of data per symbol. The higher the number of bits per symbol, the higher the data rate. For instance, BPSK transmits 1 bit/symbol, QPSK transmits 2 bits/symbol, while 64-QAM can transmit 6 bits/symbol, and 256-QAM can transmit 8 bits/symbol. Trade-Off with Signal Quality

While more complex modulation schemes can increase the data rate, they also require better signal quality to avoid errors. If the signal quality isn't sufficient, the WiFi system may need to switch to a less complex modulation, reducing the speed. So, while modulation directly impacts speed, this relationship is also influenced by other factors such as signal strength, noise, and interference. Conclusion

Modulation techniques are fundamental to WiFi technology, impacting both its data rate and signal robustness. While the trend has been towards more complex modulations to achieve higher data rates, there's an inherent trade-off with signal quality and robustness. As a result, effective use of modulation requires careful consideration of both the capabilities of the hardware and the quality of the wireless environment."

It is done using analogue techniques.

What is digital anyway? More electrons for a 1 than a 0. Analog. Or digital. Depending on whether you are measuring volts or counting electrons.

WiFi is simply transmission of a digital signal over an analogue channel

As is broadband (ADSL/VDSL) and fibre. (god knows what - SONET?)

Stop being such an ArtStudent...

Obviously my years of experience at University plus designing radios and analogue circuits to transmit both analogue and digital data. In these matters I don't need to 'refer to an authority', I *am* the f****ng authority.

No, Its wifi.

Analogue radio.

It's carrying a digital signal, sure, but only an Art Student would say that makes it to BE digital.

'Digital' TV does. And 'digital'radio. Only AM and FM are still 'analogue'

So digital TV is analogue?

Dave

The data content is digital, but the means of transmission is always analogue, whether radio, cable or fibre.

Even the most 'digital' of methods, light along single-mode fibre, has return loss, jitter and path length variation, though the latter is far less than with multimode fibre. There is also attenuation, reducing the power of the pulse continuously with distance. Again, there will be 'high' and 'low' thresholds of level which can be reliably detected, as well as a maximum timing jitter permitted.