Digital receivers

Sagax Communications, Ltd.

Haller u. 11-13. Budapest 1096 Hungary

www.sagax.hu

40 80 120 160 200 240 280 320 360 400

Instantaneous bandwidth =<Fs/2 Input bandwidth = 300MHz

Fs = 80MHz

1st

Nyquistzone

2nd Nyquist

zone

3rd Nyquist

zone

4th Nyquist

zone

5th Nyquist

zone

6th Nyquist

zone

7th Nyquist

zone

8th Nyquist

zone

9th Nyquist

zone

10th Nyquist

zone

Frequency response of the ADC input stage

F [MHz]

A

SIN

NCO

COS

MUL

MUL

Splitter

FLT

FLT

DEC

DEC

Input samples

I samples

Q samples

A A

DD

FIFOFIFO

DDCDDCFPGAFPGA

RF Front-end SDR-based Digital Receiver

DSPDSP GUIGUI

VHF/UHFVHF/UHF

LF/HFLF/HF

LAN

20-3000MHz

6KHz-32MHz

Audio

LINE

Audio,Data,

Remote

Control GPS,Compass

SERIAL

Converter card

Receiver platform computer

LPF 32MHzHPF 1.6MHz

40 80 120 160 200 240 280 320 360 400

1st

Nyquistzone

2nd Nyquist

zone

3rd Nyquist

zone

4th Nyquist

zone

5th Nyquist

zone

6th Nyquist

zone

7th Nyquist

zone

8th Nyquist

zone

9th Nyquist

zone

10th Nyquist

zone

A

RF ATT0/10/20/30dBRF Pre-selector (optional) RF LNALIMITER

Input selector

Filtered input

Direct input

A

B

RF ATT0/10/20/30dBLPF 110MHzRF Pre-selector (optional) RF LNAHPF 88MHzLIMITER

40 80 120 160 200 240 280 320 360 400

1st

Nyquistzone

2nd Nyquist

zone

3rd Nyquist

zone

4th Nyquist

zone

5th Nyquist

zone

6th Nyquist

zone

7th Nyquist

zone

8th Nyquist

zone

9th Nyquist

zone

10th Nyquist

zone

AInput selector

Filtered input

Direct input

A

B

RF ATT0/10/20/30dB

IF ATT0/10/20/30dB

LPF 3000MHzRF Pre-selector (optional) RF LNALO1

3400-6400MHz

LO22540MHz

BPF3400MHz

10MHzExt. Ref.

BPF 860MHz

LO3930MHz

BPF 60MHz(21.4MHz, 140MHz

optional)

10MHzExt. Ref.

10MHzExt. Ref.

IF AMP

IF AMP

C

D

1 2

3

AB

1

2

3

4

AB

A

B

C

D

CD

C

D

E

F

G

C

D

H

I

J

C

D

Frequency display on SRM

Frequency display on SRS

Frequency display on SRS in wb search mode

Spectrum display on SRS without (1) display decimation

Spectrum display on SRS with 2 display decimation

Spectrum display on SRS with 4 display decimation