[time-nuts] Trimble Thunderbolt 1pps

[Brian Inglis]

On 2014-01-27 23:32, Don Latham wrote:
> Mike S
>> On 1/27/2014 1:33 PM, Robert Atkinson wrote:
>>> I looked at this a while ago. The "spec" only defines transmission
>>> levels, it does NOT specify receive thresholds.
>>
>> It certainly does...
>>
>> "2.1.3 For data interchange circuits, the signal shall be considered in
>> the marking condition when the voltage on the interchange circuit,
>> measured at the interface point, is more negative than -3 volts with
>> respect to Circuit AB (Signal Common). The signal shall be considered in
>> the spacing condition when the voltage is more positive than +3 volts
>> with respect to Circuit AB (see 6.2). The region between +- 3 volts is
>> defined as the transition region. The signal state is undefined when the
>> voltage is in this transition region."
>>
>> - ANSI TIA/EIA-232-F (1997)
> wellll, maybe needed if you're running an ASR-33 teletype. . .

Except ASR-33s came with a 20ma current loop interface.
Later models added RS232 after it became popular.
ISTR TWX terminals required one and Telex terminals the other.

-- 
Take care. Thanks, Brian Inglis