# [time-nuts] Why these Crystal Frequencies?

Heinzmann, Stefan (ALC NetworX GmbH) Stefan.Heinzmann at alcnetworx.de
Thu Dec 15 05:54:19 EST 2011

```13.5 and 27 MHz are usually associated with digital video. SD video with 720 x 576 has a pixel clock of 13.5 MHz, and the corresponding SDI bit clock is 270 MHz.

Cheers
Stefan

-----Ursprüngliche Nachricht-----
Von: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] Im Auftrag von Brooke Clarke
Gesendet: Donnerstag, 15. Dezember 2011 04:13
An: Discussion of precise time and frequency measurement
Betreff: [time-nuts] Why these Crystal Frequencies?

Hi Pete:

Maybe you can shed some light on the common xtal frequencies table where there's no explanation given?
http://www.prc68.com/I/pdf/Crystal_Freq.pdf
An answer is not it's an "even" frequency or "it's an even binary frequency. That's true for most of these and the factors are part of the table above.
The question is why do they exist?
such as:
32.0 kHz
40.0
75.0
76.79
76.8
76.81
96.0
3.072 MHz
4.0
4.096
5.0
6.0
7.3729
8.0
8.192
9.8304
10.0
11.0
11.0592
11.2896
12.0
12.288
12.352
13.5
14.31818
15.36
16.0
16.384
17.734475
18.0
18.432
19.6608
19.44
22.1184
24.0
24.567
25.0
25.175
28.63636
30.0
1.4204058 GHz

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/Brooke4Congress.html

Peter Bell wrote:
> It's exactly 52 times the 1.2288MHz reference that IS95/CDMA2K uses -
> this may be a coincidence, but I somehow doubt it.
>
> Regards,
>
> Pete
>
>
> On Thu, Dec 15, 2011 at 3:46 AM, Joe Leikhim<JLeikhim at leikhim.com>  wrote:
>> I have been watching this thread and may have missed something. My
>> questions: What is the purpose of the outboard OCXO VECTRON
>> 63.8976Mhz? What model number does this RB most closely resemble?
>>
>> --
>> Joe Leikhim
>>
>> Leikhim and Associates
>> Communications Consultants
>> Oviedo, Florida
>>
>> www.Leikhim.com
>>
>> JLeikhim at Leikhim.com
>>
>> 407-982-0446
>>
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