RFbeam Microwave GmbH

RSP1 Radar Processor

Datasheet

5.4 Internal signal representation

RSP1 computes the complex amplitude spectrum of the input I/Q signals.

Analog conversion is performed with 12Bit resolution. In order to get better accuracy in fixpoint

calculations, ADC result is left shifted by 4 bits resulting in a value range from -32'768 … 32'767.

All internal processing and signal parameter settings are based on logarithmic FFT results.

This allows optimal handling of small signals and fits well to the Radar signal vs. object distance

behaviour.

Parameters returning levels such as $R02, $L00, $D00 return logarithmic scaled results

Step

Processing stage

Value range

Remark

1

Input signal (Radar Common input = 1.65V)

3.3Vpp (A=1) .. 206mVpp (A=16)

resolution 806µV/bit @A=1

2

Internal amplification

A = 1, 2, 4, 8, 16

Parameter S09

3

AD conversion 12 bit signed

-2048 … + 2047

2 channels in parallel

4

Internal representation * 16

-32768 … + 32767

used to enhance FFT accuracy

5

16/32 bit fix point FFT with Hamming window

magnitude 0 … 23'168

6

log conversion in fixpoint form x.yy

log10 as integer: 0 … 437

corresponds to 0 … 4.37

Table 3: Internal processing stages

Value

Range / conversion

Remark

Input voltage at Radar input

1.65Vp = 1.17Vrms

Gain A = 1; parameter S09= 0

Input voltage at Radar input

193mVp = 72.9mVrms

Gain A = 16; parameter S09 = 4

Maximal internal signal level

437

logarithmic magnitude level * 100

Internal signal level relation to dB

dB

≙ value / 5

Internal FFT magnitude at 1Vrms input [dBVrms] = value - 86

430 / 5 = 86

Max. input frequency

640Hz .. 11.25kHz

sampling rate / 2 (see parameter S03)

Frequency resolution

sampling rate / 256

5Hz ... 88Hz

Speed resolution

0.1km/h ... 2km/h

corresponds to 5Hz to 88Hz

Table 4: Useful signal level conversions

© RFbeam Microwave GmbH www.rfbeam.ch

December 11, 2015

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