Odd Frequency Crystal Needed

Go To Last Post
58 posts / 0 new

Pages

Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I've got a project in mind for which I will need a non-standard frequency crystal, or oscillator, for the AVR. It needs to be jitter free.

 

I need 17.145922MHz but can live with 17.146MHz +/-200Hz.

 

I could use 28.836MHz (actually 28.835840MHz)  but that'll mean serious overclocking of  a Dx part. Though I'll likely be using a Dx part anyways. It's not for a commercial project (yet) but I don't like the idea of overclocking.

 

None of the usual suspects has anything like that. I guess I could go to someone like IQD and get some cut but I have no idea what the likely costs are these days. Has anyone had custom frequencies cut in the far east?

 

Bonus points to anyone who knows what special about those frequencies.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hmm, thought it might be a multiple of one of the TV colour subcarrier frequencies - 4.4361875MHz (PAL) or 3.5795...MHz (NTSC) but nope...

 

Neil

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

barnacle wrote:

Hmm, thought it might be a multiple of one of the TV colour subcarrier frequencies - 4.4361875MHz (PAL) or 3.5795...MHz (NTSC) but nope...

 

As it happens I've got plenty of those, plus 13.5MHz and 27MHz.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

28.6363 is the colour burst multiple.

 

28.836 could be a robot vacuum cleaners radar sensor for all I know

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0


This page is usually pretty good for identifying "common frequencies" ...

 

https://en.wikipedia.org/wiki/Cr...

 

but sadly nothing like 17.14? there...

 

 

not even 34.28 either :-(

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Your best (easiest) bet is to set up a PLL chip to give the freq you want.  Not too long ago I did a board that could go from around 30 MHz to 5 GHz in 2.5 Hz steps (and they were quite precise).

At that "low" 17 MHz freq, the cost would be rather low (perhaps a couple dollars), though not 25 cents.  Old CB radios were some of the first to use cheap PLL synths. 

Maybe even some of these newfangled programmable oscillators would do the job.

 

I spent a stint on hires monitor video amps---and pixel clocks were a big thing, such as 28.835840 Meg pixels/sec

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Mon. Jan 10, 2022 - 10:58 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0


clawson wrote:

not even 34.28 either :-(

Nor 28.835840MHz.

This must be pretty specialist for no-one to recognise it

 

You are perhaps using the wrong micro. PIC32 and no doubt some ARMs have "Reference Clock" Generators with decent resolution. Which peripheral do you need to drive with this strange frequency ?

 

 

PIC32 Reference Clock Generator

 

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I think I actually have this book (or something very like it) somewherez...

Anyhow, many of these chips are super cheap (or maybe obsolete )& CB band is around your Pixel clock's freq range...worth a cheap look

 

https://www.cbcintl.com/pllbook.htm

 

 

 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Mon. Jan 10, 2022 - 11:11 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

avrcandies wrote:

Your best (easiest) bet is to set up a PLL chip to give the freq you want. 

 

I wondered about a PLL, use a standard XTAL, via a divider, into one side of the phase comparator, with the other input also fed via a divider. However, the frequency I want has very odd factors which means that my loop filter would be working with inputs of 10Hz to match an standard xtal. Not the best way to avoid jitter.

 

N.Winterbottom wrote:

You are perhaps using the wrong micro. PIC32 and no doubt some ARMs have "Reference Clock" Generators with decent resolution. Which peripheral do you need to drive with this strange frequency ?

 

Which peripheral? All of them including the CPU core.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

WooHoo.

 

Just found an eBay seller with some NOS 17.184MHz crystals. They're outside my original spec, at 0.22% high, but should work for a proof of concept.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

DDS?

Ross McKenzie, Melbourne Australia

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Perhaps look into some of the VCO/PLL for 27MHz (old)  radios, some HAM radios etc.

 

In the past I have used  different ADF4360 but it has been for VHF output.

 

If you want to go cheap, then let a tiny85 be VCO (running with internal clk) as I remember it can output 2 times CPU clk, and then make a SW PLL to a known easy to make freq. (since you never change the freq it should be easy to make with low jitter)  

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

 

 

 

If you happened to be making pixels near Nebraska

 

 

 

 

Howz about this:

=======

here's some 17.146 in Portugal  https://produto.mercadolivre.com...

 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Mon. Jan 10, 2022 - 12:54 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Not only odd number, look at this:

 

17145922 : 2 = 8572961

which is a prime number

 

calculator

 

list

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Brian Fairchild wrote:
Which peripheral? All of them including the CPU core.

So you're not giving the game away just yet then ?

 

[Edit]

grohote noticed 17145922 factorises to 2 * 8572961

Plus your other frequency of 28.835840MHz factorises to 2^18 * 11 NB: I got this wrong; see Edit

 

Hmmm - Still none the wiser.

 

[Edit]

Gah! I made a mistake with my factorising and was a factor of 10 too low: The frequency of 28.835840MHz factorises to 2^19 * 5 * 11 or ( 2^18 * 110). I may well have guessed the musical connection if I'd got the maths right.

 

Last Edited: Tue. Jan 11, 2022 - 02:19 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I Am Alone. Let Me Be In Peace. Friends Not Wanted.

 

Solitary frequency /should be on purpose OP only know/.

 

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

... not a secret if you like singing and C prime:

 

17145922 :  261.626 = 65536.002

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

grohote wrote:

... not a secret if you like singing and C prime:

 

17145922 :  261.626 = 65536.002

 

Ding ding, we have a winner.

 

Yes, I'm interested in a frequency that is 2^16 times C4. Or my 28MHz frequency is 2^16 times A4.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

avrcandies wrote:
Maybe even some of these newfangled programmable oscillators would do the job.
Five years ago

MEMSpeed Pro (Abracon)

 

Today

Abracon | Ecliptek's Quick-Turn Programmable Oscillators

Abracon | In-House Programming Service

 

edit :

Field Programming Kit | Microchip Technology

Configure Part and Sample (Microchip Technology)

 

edit2 : press release

Improve Reliability and Performance in Harsh Environments with Microchip’s New Automotive MEMS Oscillators | Microchip Technology

New DSA family introduces the industry’s first automotive-grade multiple-output MEMS oscillator, saving board space and system costs

Chandler, Arizona

March 26, 2018

[mid-page]

Development Support

Microchip’s ClockWorks® online configurator tool allows designers to order free samples and easily select the right oscillator based on frequency, package size and temperature range at clockworks.microchip.com/timing.

Automotive Timing Solutions - Microchip Technology | Mouser

 

"Dare to be naïve." - Buckminster Fuller

Last Edited: Mon. Jan 10, 2022 - 03:53 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

valusoft wrote:

DDS?

Brian, if it's about producing "tuned" musical notes you realise that using DDS you can probably create most frequencies whatever F_CPU?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Brian Fairchild wrote:
a frequency that is 2^16 times C4. Or my 28MHz frequency is 2^16 times A4.
Is there a particular reason for 2^16 times?

David

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

frog_jr wrote:
Is there a particular reason for 2^16 times?

 

Correct question, why not ATmega48 16 bit timer and 'normal' frequency

8000000 : 30578 = 261.626006  ( :15289 for Phase Correct PWM)

 

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

clawson wrote:

Brian, if it's about producing "tuned" musical notes you realise that using DDS you can probably create most frequencies whatever F_CPU?

Ah - but if you do the spectrum analysis you would not find a pure single line frequency. #1 did specify jitter free (if such a thing exists)

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I wonder if you can attach an audio system, that's so precise, to a lowly AVR that one could actually hear such jitter ? ;-)

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Brian Fairchild wrote:
It needs to be jitter free.

 

No jitter with ATtiny13A and a small smd x-oscillator at 16M, connected to PB3.

 

In hope that this will do:

 

; 30578 *2 clocks at 16M = 261.626006 Hz
aa: ldi     YH, 40
    ldi     YL, 180
bb: dec     YL
    brne    bb
    dec     YH
    brne    bb
    nop
    sbi     PINB, PB0
    rjmp    aa

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0


It's an exact pixel freq...interesting choice!

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Silabs amongst others have programmable frequency generator chips. Just Googled - Skyworks bought these off of Silabs. One part might he the SI5332. They claim ‘low jitter’. I think cypress had some offerings as well.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

clawson wrote:

]Brian, if it's about producing "tuned" musical notes you realise that using DDS you can probably create most frequencies whatever F_CPU?

 

It is indeed about that. When crunching the numbers the frequency I gave seemed optimal. It's a trade-off: jitter at the highest frequencies vs step size at the lowest frequencies vs bit width of the accumulator divider vs number of cycles to run the accumulator divider vs number of free cycles to do anything else.

 

frog_jr wrote:

Is there a particular reason for 2^16 times?

 

It means my accumulator divider can be 24 bits wide overall.

 

clawson wrote:

I wonder if you can attach an audio system, that's so precise, to a lowly AVR that one could actually hear such jitter ? ;-)

 

The human ear is an audio system. With a DDS scanned waveform that jitter shows as a frequency shift; a reasonably musical human ear can notice about 0.5% of shift of a single tone at mid-frequencies. And if you have two or more tones running together then they will beat in a varying fashion.

 

As it stands I've got a large bag of crystals on their way to me for about the same money as a couple of programmable oscillators.

 

Time to dust off my AVR instruction set summary and remember how to develop in assembler.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Brian Fairchild wrote:
As it stands I've got a large bag of crystals on their way to me for about the same money as a couple of programmable oscillators.
HF work or VHF/UHF ?

www.tokopedia.com/madagang for cheap electronics and manuscript

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Jeckson wrote:

HF work or VHF/UHF ?

 

See above posts.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

When I have needed xtals, I have used both JAN Crystals, or ICM, sadly ICM is no more, here is the contact info for JAN:

JAN Crystals
P.O. Box 06017, 2341 Crystal Drive
Fort Myers, FL 33906-6017
Telephone (800) 526-9825, FAX (813) 936-3750

 

Jim

 

 

Keys to wealth:

Invest for cash flow, not capital gains!

Wealth is attracted, not chased! 

Income is proportional to how many you serve!

If you want something you've never had...

...you must be willing to do something you've never done!

Lets go Brandon!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Brian Fairchild wrote:

I need 17.145922MHz but can live with 17.146MHz +/-200Hz.

I could use 28.836MHz (actually 28.835840MHz)  but that'll mean serious overclocking of  a Dx part. Though I'll likely be using a Dx part anyways. It's not for a commercial project (yet) but I don't like the idea of overclocking.

If you just need a binary ratio lock, keep in mind you can divide the SysCLK  by 2 in most MCUs, and that the upper MHz limits apply to FLASH fetch, and not the MHz applied to the Xtal or CLKIN. 

The simple prescaler dividers in modern MCUs are good to >> 100Mhz, the analog Xtal oscillator will stop working below that, so an external CMOS Osc is needed for going above 30~50MHz .

 

 

Kartman wrote:

Silabs amongst others have programmable frequency generator chips. Just Googled - Skyworks bought these off of Silabs. One part might he the SI5332. They claim ‘low jitter’. I think cypress had some offerings as well.

If you are experimenting, you could also look at the Si5351A Clock generator boards from Adafruit. 

Sub $10, and allows you to i2c load any magical MHz value you want (they generate a hex table via their clock builder SW) 

 

Addit: also many clones on Aliexpress, and there is a TCXO-OSC version from NT7S as Si5351A Breakout Board, but ordering on that seems to be down. 

 

I get these reports 

Inputs:   IN0: 25 MHz

Outputs:    OUT0: 17.145922 MHz          Enabled LVCMOS 2 mA          Offset 0.000 s 
Frequency Plan   PLL_A:
   Enabled Features = None
   Fvco             = 895.8744245 MHz
   M                = 35.83497728
   Input0:
      Source           = Crystal
      Source Frequency = 25 MHz
      Fpfd             = 25 MHz
      Load Capacitance = Load_08pF
   Output0:
      Features       = None
      Disabled State = StopLow
      R              = 1  (2^0)
      Fout           = 17.145922 MHz
      N              = 52.25   

( and a hint says 4.2864MHz integration bandwidth,  strangely missing from the text report ? ) 

or

 

Inputs:     IN0: 25 MHz

Outputs:    OUT0: 28.83584 MHz          Enabled LVCMOS 2 mA          Offset 0.000 s 
Frequency Plan  PLL_A:
   Enabled Features = None
   Fvco             = 893.91104 MHz
   M                = 35.7564416
   Input0:
      Source           = Crystal
      Source Frequency = 25 MHz
      Fpfd             = 25 MHz
      Load Capacitance = Load_08pF
   Output0:
      Features       = None
      Disabled State = StopLow
      R              = 1  (2^0)
      Fout           = 28.83584 MHz
      N              = 31

( integration bandwidth 7.2809Mhz) 

Last Edited: Wed. Jan 12, 2022 - 09:22 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Brian Fairchild wrote:
See above posts.

 

What intended the project ? fixed HF(a.k.a narrow bandplan) ?

 

Who-me wrote:

If you are experimenting, you could also look at the Si5351A Clock generator boards from Adafruit. 

Sub $10, and allows you to i2c load any magical MHz value you want (they generate a hex table via their clock builder SW) 

yes

 

Expecially with Arduino

www.tokopedia.com/madagang for cheap electronics and manuscript

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0



What intended the project ? fixed HF(a.k.a narrow bandplan) ?

Jeckson, ignore the rest just read #19:

Brian Fairchild wrote:

grohote wrote:

... not a secret if you like singing and C prime:

 

17145922 :  261.626 = 65536.002

 

Ding ding, we have a winner.

 

Yes, I'm interested in a frequency that is 2^16 times C4. Or my 28MHz frequency is 2^16 times A4.

The C4 in here is talking about "middle C" - the middle key on a piano - the one that plays 261.62Hz. A4 is the one above it known as "International A" (standard tuning point) at 440Hz.

 

So this is all about audible, musical notes.

 

(would this be "VLF" or is there even a name for the band of frequencies down at audible level??)

 

EDIT: Actually Google tells me that 300Hz .. 3MHz is simply "MF" = Medium Frequency, below that LF (30..300Hz) is LF = Low Frequency, in fact...

 

Last Edited: Wed. Jan 12, 2022 - 01:36 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Don't frequency bands refer to RF only, where the wavelength is proportional to the speed of light? Sound wavelengths are rather shorter...

 

Neil

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

RF = Radio Frequency

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Yeah but I was trying to put it into context for Jeckson who often posts about frequency bands in the radio spectrum ;-) 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

If my EMC consideration are wrong then my audio frequencies will be RF as well!

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Ah, we've all made 'music' with a microprocessor and AM radio receiver blush

 

Neil

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Ah, we've all made 'music' with a microprocessor and AM radio receiver blush

Wow ---that was a looooong time ago, forgot those days.  Some of the gang had codes that played decent renditions of several tunes (like happy birthday, or the futuristic 2001).

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

clawson wrote:
EDIT: Actually Google tells me that 300Hz .. 3MHz is simply "MF" = Medium Frequency, below that LF (30..300Hz) is LF = Low Frequency, in fact...
That’s AM.Meanwhile great for broadcast.

www.tokopedia.com/madagang for cheap electronics and manuscript

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Jeckson wrote:
That’s AM.

 

That is MF. Do not confuse a type of transmission with frequency range.

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I think we're misreading that frequency band chart...

  SLF is 30Hz to 300Hz 

  ULF is 300Hz to 3kHz

  VLF is 3kHz to 30kHz

 

So audio tones range from SLF to VLF.  (ok, include ELF if you can hear 20-30 Hz).

fwiw

Mike

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

grohote wrote:

Jeckson wrote:
That’s AM.

 

That is MF. Do not confuse a type of transmission with frequency range.

 

but commonly used that modulation.

www.tokopedia.com/madagang for cheap electronics and manuscript

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

mha11 wrote:

I think we're misreading that frequency band chart...

  SLF is 30Hz to 300Hz 

  ULF is 300Hz to 3kHz

  VLF is 3kHz to 30kHz

 

So audio tones range from SLF to VLF.  (ok, include ELF if you can hear 20-30 Hz).

fwiw

 

I maintain my argument that audio tones are not intended to be characterised by those frequency range descriptions. Radio waves - at any frequency - are transmitted at the speed of light and their wavelengths are correspondingly long. Audio is a compressive wave in a physical medium, and the speed of sound differs depending on the material and their wavelengths, irrespective of material, are orders of magnitude smaller than those of radio.

 

We're in danger of comparing apples with oranges.

 

Neil

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Radio waves - at any frequency - are transmitted at the speed of light and their wavelengths are correspondingly long. Audio is a compressive wave in a physical medium, and the speed of sound differs depending on the material and their wavelengths, irrespective of material, are orders of magnitude smaller than those of radio.

Interesting to think of RF broadcast at "near audio" freqs...long ago (were the mid 80's that log ago?) worked on some Loran rcvr circuits that are broadcast (RF, not sound) at 100 kHz   ...but we used some standard cheapo audio transformers in the antenna "tuning" section, rather than "RF" coils! Interesting to build an RF rcvr out of "audio" parts. Loran was pretty cool for its day, there may still be a few remnants in existence.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Jeckson wrote:
but commonly used that modulation

 

I should agree, if we were back in Sixties.

 

Today most of AM broadcasting stations are gone. Including mighty 1MW EU-giants that every night were loud and clear on southern latitudes up to South Africa.

 

Ever heard of 500 and 2182kHz? No longer active for sea-mans.

 

Should I say R.I.P. - I do not dare. AM remains a nice memory, and is so sad speaking about a final digital verdict.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

avrcandies wrote:

Radio waves - at any frequency - are transmitted at the speed of light and their wavelengths are correspondingly long. Audio is a compressive wave in a physical medium, and the speed of sound differs depending on the material and their wavelengths, irrespective of material, are orders of magnitude smaller than those of radio.

Interesting to think of RF broadcast at "near audio" freqs...long ago (were the mid 80's that log ago?) worked on some Loran rcvr circuits that are broadcast (RF, not sound) at 100 kHz   ...but we used some standard cheapo audio transformers in the antenna "tuning" section, rather than "RF" coils! Interesting to build an RF rcvr out of "audio" parts. Loran was pretty cool for its day, there may still be a few remnants in existence.

 

There are still time signals broadcast from the UK, from Germany, and I think from the US, on 50kHz and 60kHz. And the US (and probably other) navies transmitted to submarines on very low frequencies; such being the only radio signal that would penetrate deepish waters. The data rate was a bit low, though, measured in fractions of bits per minute. :)

 

There is a possibly apocryphal tale of a Russian power grid that stretched the full length (width?) of the country; they shoved lots of power in at one end at got nothing out at the other as it was all being radiated at 50Hz...

 

Apropos low data rates: when I was working with deep drills, communication from the top to the robot was by changing the speed of the drive motor by a bloke with a stop watch and his hand on the throttle. Bit rate was about one every two minutes. The return data modulated the lubricating mud return pressure...

 

Neil

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Today most of AM broadcasting stations are gone.

What?? The dial is very crowded with AM talk-radio...we live just a few minutes from the old monster WLW transmitter....it is an interesting tour!

 

http://j-hawkins.com/wlw.shtml

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The disappearing disease started from most powerful stations, because the people is suddenly becoming aware of radiations, and there are financial problems, too.

One of most interesting big closing was Vatican radio, 1530kHz.

Of course that the small AM station will survive- which is not the case with Short wave stations (3...30MHz), they are doomed I am afraid.

 

 

Pages