Hacker News Reader

Comment by Johnythree | Hacker News Reader

As a radio hobbyist I found this fascinating.

There is a large amount of literature on the design of old-style radio circuits (MF and HF, eg shortwave), but surprisingly little available on the design of modern VHF/UHF consumer electronics.

In particular I found it interesting how the manufactures coped with the crazy proliferations of different TV broadcast standards around the world.

The authors home page at https://www.maximus-randd.com/ looks like being a huge source of interesting reading for RF enthusiasts.

View on HN

I found this page when searching for the ICs in (what I now know is) a tuner module. Surprised that this site has never been posted to HN before. I'm working on FMCW radar related stuff so it was super interesting to me too.

I found it sometime last year, looking for data on a Philips video IF processing chip, I thought about posting it. Great site from an interesting guy, a rather sad history of the decline of electronics manufacturing in western europe though, death by bean counters.

What was the IC you were looking for, PLL synthesizer or Demodulator?

I was just curious about the chips inside one of these tuner modules, so I searched up their label and went to images. The two things are TDA5737 and TSA5522, which seems to be mixer and synthesizer.

I think it's because old radio circuits were topologically fairly simple but designed using priceless experience and big budgets (e.g. tangentially Tektronix had a scope with synthetic sampling rates in the THz in the 60s or so), whereas modern stuff is becoming - even in simple designs - harder and harder to analyse as margins are being chased.

You can usually work out the basics by finding out the main working chips in a product and reading their application notes - as long as it's not Chinese it should be well documented.

THz? That's interesting but seems hard to believe. Do you have some pointers?

Tektronix 7T11 system - up to 10 ps/div (at ~15 GHz or so analog bandwidth with the right sampling head), ~250 samples per trace (~10 divs wide), so one sample every 100/250 ps = 0.4 ps = about 2.5 THz ETS rate. Whether this really says so much about the system ... I'm pretty sure that the sampling jitter exceeds 0.4 ps by quite some margin. In a system constructed like this it is actually really easy to turn the ETS rate up to incredibly high values; whether the data that generates is useful, is another question.

This was a fully analog system hence the ~.

I assume GP is talking about equivalent-time sampling. ETS is a technique for extending sampled system bandwidth at the expense of requiring a perfectly repetitive waveform. Consequently, it's useless for single-shot captures, where you only get the native sample rate of the system.

ETS used to be much more common in the days before (affordable) digital oscilloscopes could directly sample at high enough frequencies to be useful.

Keep in mind it's a synthetic sampling rate too.

Equivalent time sampling

"(e.g. tangentially Tektronix had a scope with synthetic sampling rates in the THz in the 60s or so), whereas modern stuff is becoming - even in simple designs - harder and harder to analyze as margins are being chased."

Yeah, yet another sad engineering story is modern documentation—or more precisely the almost complete lack thereof. One of the great things about Tektronix was that it was an electronics instrument company run by engineers—engineers who were truly committed to both technical excellence and the highest quality of manufacturing [at least that was my experience of the company back some decades ago when I was buying its CROs and analyzers—I'm unsure of the current situation].

Rigorously complying with technical standards was a Tektronix mantra—and that included supplying customers/users with top-notch, high quality documentation. Tektronix user and service manuals were legendary for not only being both comprehensive and clear to understand but also for their ergonomics—you could find any info needed about an instrument within seconds (the manuals were ergonomic design masterpieces).

Unlike most of today's equipment where most of the technical information about a device is considered proprietary and held locked up by corporations, Tektronix manuals provided the customer with just about everything a customer wanted to know: detailed technical descriptions of its electronics operation, clear and comprehensive circuit diagrams with layouts including parts cross references together with properly indexed parts lists for purchasing spares. [Right, back then, there was none of this current fight about the 'Right to Repair' as that was the assumed norm by both users and manufacturers alike - yes, we had the 'Right to Repair' and it was stolen from us.]

That Tektronix published such detailed information for everyone to read is proof that patents, copyrights and manufacturing trade secrets alone could protect the company's IP. It demonstrates the fact that it is unnecessary to hide almost everything about equipment except its bare operational details.

Tragically, the problem about the paucity of information about equipment coming from manufacturers these days has now been around so long that both younger users and engineers simply do not know what decent equipment documentation looks like or entails. For those who don't then I'd suggest you have a look by downloading the Tektronix 7834 oscilloscope manual from the Internet Archive (this is a device that I'm very familiar with):

https://archive.org/details/tektronix_7834

(Note: for a better quality presentation, download the PDF version without the embedded text; alternatively download both versions.)

INCIDENTALLY, NOTE THAT 'TROUBLESHOOTING', P-4.3; 'CORRECTIVE MAINTENANCE', P4.12; AND THE SPARE PARTS LIST, P7.1, ARE ALL COMPLETE AND WITHIN THIS ONE SINGLE MANUAL. IT'S PROOF THAT BACK IN THE 1980S AND BEFORE THAT THE 'RIGHT TO REPAIR' WAS AUTOMATICALLY ASSUMED BY EVERYBODY!

Finally, I'd add that today's practice of locking up equipment information behind corporations' firewalls—information that only a few decades ago was freely available from many tech manufacturers—has the negative effect of deskilling* the population. Not only this but also it wastes considerable time and effort as users have to try and discover (or reverse engineer) info that rightfully ought to be in equipment manuals (consider the total productivity loss when taken across the full population of users).

* For example, Tektronix manuals were wonderful training aids for those wishing to understand how an oscilloscope works. With the aid of a second oscilloscope and the manual of the first, one, say, could trace the passage of signal from the vertical input amplifier to the defection plates, etc., etc.

Although the kind of training-documentation a la Tek is dead, Analog have some rather nice docs for the things they care about - for their SDR-on-chip chipsets they have long form (600page) books to read.

There's also the problem that a modern scope is just a maze of ASICs, FPGA blobs, etc.

"just a maze of ASICs, FPGA blobs, etc."

Right, I know. That's another serious issue much too big to discuss here except to mention two well-known examples that highlight the problems:

1. There's are problem with having compiled, thus obfuscated, code in embedded devices such as you mention. The high profile case being the Volkswagen emissions affair. Given the potential for vehicles (normal or EV) to kill people, there's a strong case that all such embedded code in mission-critical applications ought to be open whether the manufacturer likes it or not.

2. Backdoors such as Intel's Active Management Technology/AMT/IME should not be allowed by law unless all aspects of their APIs are published openly.

It's not only high profile stuff such as I've mentioned either. Several weeks ago I bought a NETGEAR LB2120 4G/LTE modem. I know nothing about the information it sends back to NETGEAR other than it actually does so by virtue of the fact that it advised me of an update (no other information about the update was supplied). It seems to me that, as user, I not only have the right to know what information is sent back but also that I should have the option to block it—and that this right should be enshrined in law.

Reply on news.ycombinator.com