ZHC618F-3000W Compact FM Stereo Transmitter

1. Overview

ZHC618F-3000W stereo FM radio transmitter is an integrated high-quality FM transmitter that stereo-encodes the input left and right channel audio signals and adjusts the FM modulation to the broadcast band, then RF amplify to the 3000W output power for wireless broadcasting. The transmitter adopts the most advanced software radio technology to achieve the international leading level of product performance indicators.

With a new large-scale field-programmable gate array (FPGA) and direct digital frequency synthesis (DDS) technology at up to 5G, the product achieves the highest technical specifications in the industry to date, providing listeners with a CD-like sound experience.

The product consists of audio interface unit, digital processing and frequency modulation unit, RF power amplifier unit, human-machine interface unit, communication interface unit, clock synchronization unit and power supply unit. The transmitter is installed in a 19-inch 4U standard chassis, intensive design, small size and light weight. The whole transmitter is designed with high reliability, which makes the product run continuously and stably for a long time.

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):

◆ AES/EBU digital audio signal input (highest priority)

◆ Analog stereo analog audio signal input (2nd priority)

◆ MPX stereo composite signal input (3rd priority)

• Supports one RDS or SCA subcarrier input

• 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 communication interface

• 19-inch standard chassis, height 2U

The Transmitter Block Diagram:

3. Technical specifications

Electrical Specifications:

1. Frequency Range                           87MHz～108MHz

(other frequencies can be customized), stepping 10kHz

2. Carrier frequency tolerance     ±200Hz

3. Output power              0~3000W continuously adjustable

4. Output power tolerance       ±1dB

5. Output impedance           50Ω

6. RF output connector         7/16” or 7/8”

7. Residual wave radiation       < -70dB

8. Parasitic amplitude modulation noise    < -50dB

9. Pilot frequency deviation          ±0.1Hz

10. 38KHz residual component in the S signal < -50dB

11. 100% modulation frequency offset    ±75KHz

(maximum modulation frequency offset 112.5KHz)

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

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

14. Stereo separation        ≥73dB (L → R, R → L)

15. Distortion            ≤0.01% (30Hz ~ 15000Hz, 100% modulation)

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

                                                   ±0.05dB (emphasis, de-emphasis)

17. Left and right channel level difference  ≤0.01dB (100% modulation)

18. Analog audio input              -12dBm ~ +8dBm

19. Analog audio input impedance      600Ω balance

20. AES input impedance            110Ω balance

21. AES input level                0.2~10Vpp

22. AES sampling rate             30kHz ~ 96kHz

23. RDS input impedance           10kΩ unbalance

24. RDS input level               0dBm

25. MPX input impedance           10kΩ unbalanced

26. MPX input level                1.0Vpp

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

28. Heat dissipation method         Forced convection

29. Power supply voltage           100VAC~265VAC/ 47Hz~63Hz

Physical Specifications:

30. Chassis standard            19" inch

31. Chassis size                  4U（680mm X 485mm X 176mm）

32. Total weight              55Kg (including packaging)

33. Operating environment temperature  -10 ° C ~ +45 ° C

34. Relative humidity               <95%

35. Altitude                     <4500m