DL9SEC DDS-VFO (small)
with DRM receiver frontend



1. The DDS-VFO

Click for a large view of the DDS-VFO block diagram

Fig. 1: Block diagram of the DDS-VFO

Features of the DDS-VFO:
  • Frequency range from 0,500.0MHz to 39,999.9MHz
  • Possible frequency steps are 100Hz, 1kHz, 10kHz, 100kHz, 1MHz
  • Power range from -40dBm to +10dBm (-40dBm, -30dBm, -25dBm, -20dBm, -15dBm,
    -10dBm..+10dBm in 1dB steps)
  • Harmonics rejection at +10dBm output power better than 40dBc
  • Microcontrolled (firmware flashable)
  • 16x2 LC display with LED backlight
  • 5 button keypad and rotary dial
  • Idicator LED and beeper
  • Generator and receiver mode
  • Adjustable IF (1kHz..460kHz) in receiver mode
  • Fixed output power (+7dBm) in receiver mode
  • "One-touch" switchable LO shift (above or below fr) in receiver mode
  • Automatic save of the all parameters after 3 seconds
  • Remote frequency control via RS232 (acts as a Yaesu FT-817)
  • Slot for extension (e.g. the DRM receiver frontend)

2. The DRM receiver frontend

Click for a large view of the DRM-RX block diagram

Fig. 2: Block diagram of the DRM receiver frontend

Features of the DRM receiver frontend:
  • Input frequency range from 0,5MHz to 30MHz
  • FET preamplifier for short antennas
  • Double superhet (1st IF 455kHz, 2nd IF 12kHz)
  • Output amplifier and buffer for direct connection to a PC soundcard (line in)
  • For use with a DRM decoding software (e.g.External linkDReaM)











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Last update at 21.03.2005 by Thorsten Godau DL9SEC