This manual introduces the features and usage of Chonghan CH-M1 wireless Modem.
This manual describes the CH-M1 series wireless modem, covering safety and hazard warnings, legal liability, and proper usage environments. It explains that the device must not be used near explosive operations, medical equipment, or on aircraft, and outlines the responsibilities and limitations of the manufacturer.
The guide also details the modem’s communication features, including supported frequency bands, SMS capabilities, dialing settings, and typical performance figures. Reference tables list model variants (GSM/GPRS and CDMA), and a FAQ section answers common questions about SMS length, sending rates, SIM compatibility, and troubleshooting. This manual is written in Chinese.
| Default modem baud rate | 19200 bps |
|---|---|
| Maximum SMS length | 140 English characters or 70 Chinese characters |
| Typical SMS sending rate | ≈750 messages per hour per modem |
Each SMS can contain up to 140 English letters or 70 Chinese characters, including spaces and punctuation; mixed English counts as Chinese characters.
Under normal network conditions, a CH-M1 modem can send about 750 SMS messages per hour.
No. The modem must be turned off and cannot be used on any aircraft, whether on the ground or in flight.
No. A CDMA SIM card cannot be used in a GPRS modem; you need a CDMA modem for CDMA cards.