[ICOM] Shaft Encoder vs pot?

[marditti at dslextreme.com]

Jennifer,

DDS stands for Direct Digital Synthesis.  This is the method by which the
radio generates the actual receive and transmit frequencies.  This is a
digital process and requires input pulses to step up or down the
frequencies.  These pulses are typically generated by an encoder.  This
encoder is on the shaft of the frequency control knob.  Another method to
ender a specific frequency is to input the DDS is directly from keypad or
computer.  Under these conditions, the encoder is not part of the process.
 The 'earlier' digital control radios the frequency control was through a
Phase Lock Loop (PLL) process.
This is a very short and basic explanation and I hope it helps.

73,

Mort,  KB6BSN


Jennifer
> Just wonder, is that the same as a DDS Encoder?
>
>
> At 10:55 AM 4/29/2008, you wrote:
>
>>Ken,
>>
>>The major difference between a variable resistor and shaft encoder is as
>>follows.
>>A variable resistor typically has three terminal.  The total or maximum
>>resistance is between two of these terminals. The third terminal
>>resistance in respect to the other two is continuously variable.
>>An encoder is a digital unit that creates a position code relative to the
>>shaft rotation.  Some encoders may just provide pulses relative to the
>>rotation and the direction of the rotation. Other encoders may also
>>provide an output which may reflect the absolute shaft position.
>>In car radios, the detentes can be there as a tactile feedback.  The
>>actual function cab be a variable resistor or encoder.
>>
>>This is just a very brief explanation.  I hope that it helps.
>>
>>
>>Mort,  KB6BSN
>>
>>ken.holland at evonik.com
>> >
>> >
>> > Hello all,
>> > Just a short question here, what is the difference in a *shaft
>> encoder*
>> > (as
>> > used in the 756 Pro PBT encoder) and a "variable resistor" or pot?  I
>> have
>> > wondered that when turning the volume knob on car radios - they seem
>> to
>> > have many little "detents" as you turn the knob.  Just what info is
>> being
>> > sent to the processor?  Pots I understand, but not *encoders*.
>> >
>> > Thanks for any info.
>> >
>> > Ken H>
>> > K9FV----
>> > Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
>> > Icom Users Net: Sundays, 1700Z, 14.316 MHz
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>> >
>>
>>----
>>Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
>>Icom Users Net: Sundays, 1700Z, 14.316 MHz
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>
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> ----
> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
>