500mW DATA RADIO MODEM

I. Features of ET-LEM series Data Radio Module

1-The transmission power is 500mw (27dB). You can order 20dB or 29dB.If you need the 10dB transmission power, the type is ET-UEM.

2-High receiving sensitivity: the max sensitivity is –124dBm/1200bps.

3-High anti-interference and low BER (Bit Error Rate). Based on the GFSK modulation mode, the high-efficiency forward error correction channel encoding technology is used to enhance data’s resistance to both burst interference and random interference ,meanwhile the actual bit error rate  can be achieved 10^-5～10^-6 when channel bit error rate is 10^-2.

4-Long transmission distance Within the range of visibility, the max reliable transmission distance is 4Km (BER=10^-3/1200bps) when the antenna height is greater than 2m,the reliable transmission distance is more than 2Km(BER=10^-3/9600bps).

5-Using for industry/army Because of adopting the high quality component and high reliable TCXO crystal, the temperature can achieve -35℃ to +80℃ ( industry grade).

6-Transparent data transmission Transparent data interface is offered to suit any standard user protocol. Any false data generated in the air can be filtrated automatically (What has been received is exactly what has been transmitted).

7-Multi-channel The standard ET-LEM series configuration provides 8 channels. If the user needs, it can be extended to 16/32 channels, meeting the multiple communication combination mode of the user.

8-Three kinds of interface modes(TTL 、RS-232 、RS-485) RS232, RS485 interface diversion chip,DB9 standard interface connector and special power connector are used.

9-large data buffer zone Interface baud rate is 1200/2400/4800/9600bps with format of 8N1/8E1 and user can define it by himself. It can transmit unlimited data when Interface baud rate is not bigger than air effective baud rate band.

10- Intelligent data control and the user does not need to prepare excessive programs. Even for semi duplex communication, the user doesn’t need to prepare excessive programs, only receiving/transmitting the data from the interface. ET-LEM series will

automatically complete the other operations, such as transmission/receiving conversion in the air, controlling, etc. 11 ET-LEM can indicate the power source and the data’s transmission and receiving.

II. Application of ET-LEM series Data Radio Module

Series ET-LEM data RF module is suitable for:

Matching for the exports;
Communication of army and police;
Data transmission system for railway, electricity and oil field;
Industrial remote controlling and remote testing, automatic data collecting system

III. How to use ET-LEM series Data radio module

ET-LEM Series Radio provides three interface modes including standard RS-232, RS-485 and UART/TTL levels allowing direct connection with computer, user’s RS-485 device, SMC or the other and other UART components for application. The using method is showing as follows

1.Power supply ET-LEM uses DC power supply with voltage of +5V. We suggest not to use the switch power or boosted circuit. But if you have to use, please pay more attention to the interference of power switch pulse on RF module. You had better choose the switch power of higher frequency. Of cause the linearity power is better. If you can separate module from other equipment by optocoupler, meanwhile separate module power from other equipment power by linearity power, the communication quality will be better.

2.Definition of ET-LEM series connecting terminal ET-LEM series can supply one 2P power connector and one (DB9) data pin connector, and its definitions as well as connection method for terminals are shown in Table 1. Table 1 and table 2.

Table 1: Definition of 2P power supply interface pins and connection method

Table 2: Definition of DB9(positive) interface pins and connection method

The sleep function cant be used. If you want to use it, Please inform us when you order.

3.Setting of channel, data format and the interface baud rate:

Before using ET-LEM, the user needs to make simple configuration based on his own needs to determine the channel, data format and the additional function. There is a switch of 8 bits on the ET-LEM. When turn it to “ON”, it means 0 and the opposite means 1.

Note: When choosing the code switch every time, the choice will be effective after the power supply start again.

a. Channel configuration:The 1,2,3 bit on the switch provide 8 channel options, and the user can choose to use 0-7 channels through them. Within one communication network, as long as the operation mode of switch is the same, it can be communicate with each other. The standard set in factory is 7 channels, SW321=111(7). Frequency :433.926MHz The corresponding frequency of the other channel is as follows (table 3)

Table 3: Corresponding frequency points of 0～7 channels

b. Checkout mode selection:ET-LEM can support no checkout and parity checkout modes, that is 8N1/8E1.You can choose checkout mode through the fifth bit of the switch: The standard set in factory: 5^th bit =1,8E1(even parity)

5^th bit=1 8E1 (even checkout)
5^th bit=0 8N1 (no checkout)

c. Selection of interface data baud rate: We can set the interface baud rate in order to satisfy different demands of customers. It can be set through the 7,8 bit on the switch.

In order to achieve the best communication quality, the air communication baud rate of ET-LEM serial is relation to the hardware of ET-LEM, so it can’t be changed after selling. The data following the LEM is air effective baud rate, for example:

ET-LEM12 means the efficiency baud rate in air is 1200bps ET-LEM192 means the efficiency baud rate in air is 19200bps The model of the LEM serial in our company is as follows:

ET-LEM12, ET-LEM48, ET-LEM96, ET-LEM192, ET-LEM384.

Interface baud rate is different from the air baud rate. Each kind of LEM provide 4 kinds of interface baud rate for the selection of customer, as table 4

Table 4: The selection of interface baud rate

Because the buffer zone is limited in RAM of LEM ,when the interface baud rate is bigger than air efficiency baud rate for ET-LEM12 and ET-LEM48, if the user want to send the long data at one time, the data may be lose because of the overflow of the buffer zone. So it is better for user to send the smaller data packet. the longest data you can send each time is as table 5.

Table5: the longest data time as different the interface baud rate When the interface baud rate is smaller than the air efficiency baud rate, theoretically, you can send infinitude long data packet but we advise you not to send the long data packet. We suggest the data length for each packet is between 60 Byte and 100 Byte. It should not longer than 120 Byte, meanwhile, it is better for user to use the ARQ mode to resend the mistake data packet. The analysis is as follows;

• Model: ET-LEM96 500mW
• 0 Units in Stock
• Manufactured by: EasyTele

This product was added to our catalog on Sunday 30 December, 2007.

Type	Interface baud rate	Allowed longest data
ET-LEM12	2400bps	500Byte
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