[TenTec] Scads of used Icom IC-7300

[Carl Moreschi]

There's no law that says the step size has to be 1 mv.  It can be 
whatever the design allows.

Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com

On 9/11/2016 5:04 PM, Gary J FollettDukes HiFi wrote:
> I understand and appreciate this discussion of NOISE dynamic range. This does not explain how one can get SIGNAL dynamic range higher than ~96 dB with 16 bits. These are different quantities.
>
> If the A to D has say, 1 mV per bit response, then the largest input signal this 16 bit A to D can measure should be ~65,000 mV. That’s about 96 dB. Please tell me what I am missing here…
>
> Is the input amplifier compressing the RF input signal dynamic range range to make this work? This was done on Vinyl records to compress the roughly 120 dB dynamic range of an orchestra down to the 70 dB or so that Vinyl records could carry.
>
> Gary
>
>
>
>> On Sep 11, 2016, at 6:49 AM, shristov<shristov at ptt.rs>  wrote:
>>
>>
>> Gary J FollettDukes HiFi wrote:
>>
>>> How is it that a 16 bit A to D can now handle a
>>> dynamic range of 132 dB (in band)?
>>
>>
>> A perfect 16-bit ADC would have a difference of 97.8 dB
>> between the average noise level and the level of the full-scale
>> sinusoid. This is a basic fact, and it is NOT violated by ADCs
>> used in SDR receivers. In fact, a real-life 16-bit RF ADC
>> has substantially less than 97.8 dB.
>>
>> Under certain conditions, not very difficult to fulfill,
>> ADC noise spectrum density is uniform, i.e., there is
>> the same average noise level in each Hz of the ADC output.
>>
>> Now, if the ADC output goes through a filter with
>> the bandwidth smaller than half of the sampling
>> frequency, the average noise power AFTER the filter
>> will be decreased in proportion to bandwidth reduction.
>>
>> For example, if the bandwidth gets reduced from 50 MHz
>> to 500 Hz, i.e. 100,000 times, the resulting average noise
>> level will be decreased by 50 dB.
>>
>> So, one might say that the ADC dynamic range got increased
>> from 97.8 dB to 147.8 dB (minus imperfections).
>>
>> Such an interpretation would not be correct if the essential
>> factor of bandwidth reduction is omitted.
>>
>>
>> 73,
>>
>> Sinisa  YT1NT, VE3EA
>>
>>
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