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The 5G series of FM radio transmitters with true CD sound quality are put into production


1. Overview

ZHC5G series FM stereo broadcast transmitter (exciter) is an outstanding software radio product; it is designed with high reliability concept and has unparalleled performance indicators.


This transmitter uses a new large-scale field-programmable gate array (FPGA) and direct digital frequency synthesis (DDS) technology up to 5G, which has achieved the highest technical specifications in the industry so far, it’s providing listeners with CD-like sound quality.


The transmitter consists of audio interface unit, digital processing and FM modulation unit, radio frequency power amplifier unit, human-machine interface unit, communication interface unit, clock synchronization unit and power supply unit. The transmitter is installed in one 19-inch 2U standard case, and all input and output signals are led out from the rear panel.


2. Technical characteristics and principle block diagram

Product technology has the following technical features:

• Full process digital processing to achieve a perfect auditory effect of CD-like sound quality

• Full-scale digital processing with large-scale field-programmable gate array (FPGA) technology

• Direct digital frequency synthesis (DDS) technology at speeds up to 5G to peak transmitter specifications

• High reliability microprocessor (ARM) technology as the primary controller

• Support for multiple audio source inputs (transmitters can be automatically selected by priority):

Two AES/EBU digital audio signal inputs (highest and second priority)

One analog stereo analog audio signal input (3rd priority)

One MPX stereo composite signal input (4th priority)

One I2S digital audio signal input (lowest priority)

• Supports one RDS or SCA subcarrier input

• Support stereo pilot signal and stereo composite signal 19KHz/MPX output

• Upgradeable to FM Synchronous broadcast transmitter

• Electronically controlled AGC controls output power zero drift

• Perfect over-current, over-voltage, over-temperature, over-power, standing wave ratio alarm and protection

• One-touch shuttle quick keyboard input

• Real-time display of operating parameters using OLED

• With TCP/IP, RS232, RS485, CAN communication interface and SMS modem interface

• 19-inch standard chassis, height 2U


The Transmitter Block Diagram:

New Digital FM Transmitter Block Diagram.jpg


3. Technical specifications

1. Nominal emission frequency            87MHz108MHz

(other frequencies can be customized), stepping 10kHz

2. Carrier frequency tolerance             ±200Hz

3. Output power                           030W/0100W/0300W

4. Output power stability                  <±3% (ambient temperature -10 ~ + 50 )

5. Output impedance                      50Ω

6. RF output connector                    N-50K

7. Residual wave radiation                <-80dB

8. Parasitic amplitude modulation noise   <-55dB

9. Analog audio input impedance          600Ω balance

10. Analog audio input level               -12dBm ~ +8dBm

11. AES input impedance                 110Ω balance

12. AES input level                        -60dBFS0dBFS

13. MPX input impedance                 10kΩ unbalanced BNC

14. MPX input level                       -15dBm+15dBm

15. Input audio Level Gain                -15dB~+15dB Step 0.1dB

16. RDS / SCA input                      Unbalanced BNC

17. Audio pre-emphasis                   0μs/25μs/ 50μs/75μs optional

18. Signal-to-noise ratio                  92dB (1kHz, 100% modulation)

19. Distortion                             <0.01% (30Hz ~ 15000Hz, 100% modulation)

20. Frequency response                   ±0.01dB (no emphasis, no de-emphasis)

±0.05dB (emphasis, de-emphasis)

21. Stereo separation                     73dB (30Hz15000Hz)

22. Left and right channel level difference <0.01dB (100% modulation)

23. 19KHz / MPX output impedance       600Ω, unbalanced BNC

24. 19KHz / MPX output level             -15dBm + 15dBm

25. Heat dissipation method               Forced convection

26. Power supply voltage                  90VAC~265VAC/ 47Hz~63Hz

27. Chassis standard                      19" inch

Size 2U (width 484mm × height 88mm × depth 500mm)

28. Total weight                           15Kg

29. Operating environment temperature   -10 ° C ~ +50 ° C

30. Relative humidity                      <95%


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