LF Receiver and transmitter

[davidramirez]

Hi i Work with FXTH871511DT1

I try to understand LF receiver but i have two questions.

1- I can transmitt data with PWM to 125Khz coded to manchester and FXTH87 i can see the data that i sent, or i need a carrier signal to envelop the data to trasmitt.

2- If i need to carrier to transmitt the data How i can do it? I can generate 125Khz frequency and RC filter to 125Khz base-band and antenna or i need something else to modulate the data.

[TomasVaverka]

Hi David,

I guess your question regards the LFR in data mode reception, otherwise, for carrier mode a simple 125 kHz has to be sent with strong enough amplitude and duration according to the detect time required to validate the carrier (LFCDTM).

In data mode, you have to modulate the 125 kHz with the frame described in the data sheet (Telegram format). You can use whatever tool you have in hands. In lab environment, we are personally using an AFG (Tektronix AFG3022) for the sending of the telegram, this telegram being separately generated in excel file and converted in a format readable by the AFG/AWG used.

One can equally use directly an RF generator for the 125 kHz generation (for example Rohde&Schwarz SML01), and modulate the 125 kHz generated, by the telegram at its Mod input. Here again, the data stream (telegram) has to be generated separately (without the 125 kHz inside this time around).

Hope this helps.

Best regards,

Tomas

[davidramirez]

Thanks.

I have a other question, for LF receiver there are two mode MCU Direct and Data Mode, and that this device wake up when a carrier o a Manchester datagram is detected.

My question is can I send manchester datagram without carrier to 125 KHz frequency ?