[time-nuts] Re: Clock displays -- eye response

[Brooke Clarke]

Hi Jim:

Interesting paper on flashing temporal response.

 Â "Have Quick" is primarily a spread spectrum radio protocol but it also includes a time transfer/setting protocol.
The early Trimpack GPS receivers included a time setting output.
https://prc68.com/I/Trimpack.shtml

The PLGR & DAGR output the HQ digital data used to set the time in the O-1814 Rb.  The O-1814 was part of the Program 
Pacer Speak System so that inbound bombers coming from far away would hear the HQ radio transmissions.
https://prc68.com/I/MT6250.shtml

There are different flavors of HQ time protocol, but the newer one just adds data after the older one so is backward 
compatible.

It's tricky to see the data.  I needed to use an SRS DG535 to delay the scope trigger so that I could use a very fast 
sweep speed.
https://prc68.com/I/DAGR.shtml#HQ1PPS - scroll down a little to see the HQ setup.

-- 
Have Fun,

Brooke Clarke, N6GCE
https://www.PRC68.com
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.

-------- Original Message --------
> On 12/10/21 12:31 PM, Brooke Clarke via time-nuts wrote:
>> Hi Hal:
>>
>> There has been some recent research into illusions related to sight and sound.
>> https://en.wikipedia.org/wiki/McGurk_effect - related to speech
>> and search "audio optical illusion"
>>
>> I like a crisp "tick" for clock human synchronization.
>>
>> I wonder why there has not been more done with military "Have Quick" for time synchronization?
>> https://en.wikipedia.org/wiki/HAVE_QUICK
>
> HAVE QUICK was a very early hopping spread spectrum system and was long since superseded by SINCGARS and other systems 
> in the 1980s. I don't know that it is a "source" of time.
>
> There was a whole set of systems for loading "time" into these frequency hopping systems, since all manner of their 
> synchronization behavior depended on time.  And in usual DoD/NATO fashion, forward and backward compatibility was 
> often required, so you'd have a way to sync any two random radios in a battlefield situation.  Cryptographic keying is 
> also often time based, as are frequency nets (local interference, keeping the other guy guessing, or propagation changes)
>
> Synchronization is the "hard part" of most spread spectrum systems both Direct Sequence (PN codes) and Frequency 
> Hopping, and that's where most of the classified stuff is - how do you synchronize reliably, how do you prevent the 
> synchronization from being spoofed or jammed. A naive FH approach is to have a "hailing channel" and the first person 
> transmits there, and the other person hears it, listens to a sync pattern, and then commence hopping together. This 
> works for point to point between two stations, but doesn't work very well when you have multiple stations, not all of 
> which can hear each other.
>
> GPS would have been a godsend back then (although it's not very good from an Anti Jam standpoint).
>
>
> Dixon, in the seminal tome "Spread Spectrum Systems" kind of makes an offhand comment that synchronization is the 
> challenging part, and then moves on "assuming we have synchronized".
>
>
>> It's been a part of the PLGR and DAGR GPS receivers and I expect also for the military embedded versions for a long 
>> time.
>> https://prc68.com/I/PLGR.shtml#Time
>> https://prc68.com/I/DAGR.shtml#HQ1PPS
>> Also things like the O-1814/GRC-206 Reference Frequency Rb Oscillator make us of it.
>> https://prc68.com/I/O1814.shtml
>>
> I don't know that they make use of it, rather, they can provide sync TO a HAVE QUICK radio.
>
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