RF transmitter and reciever that works on both 315 mhz and 433 mhz ?

[burrow]

I am totally confused. I messaged a few RF module sellers to ask if their product is 315 mhz or 433 mhz. and i got reply from many of them that it supports both .
I really don't understand what do they mean. I am sure its not the one with switch or anything to select one frequency(because they are cheap modules ) .Also one seller messaged me saying they share common receiver and only transmitter is different. Please throw in some light to this doubt

 

[FvM]

This sounds unlikely. Both transmitters and receivers have resonant LC circuits dimensioned differently for both bands. All modules that I know, either single fixed frequency or channel programmable have to be ordered for a specific band.

Technically, the output filter must be designed for a specific frequency band to achieve impedance matching and sufficient harmonic suppression. Receivers could be possibly multi-band, but I didn't see any yet.

 

[D.A.(Tony)Stewart]

Most used SAW resonators with clearly marked frequency and many no longer active due to reliability issues with temperature etc.

 

[burrow]

This sounds unlikely. Both transmitters and receivers have resonant LC circuits dimensioned differently for both bands. All modules that I know, either single fixed frequency or channel programmable have to be ordered for a specific band.

Technically, the output filter must be designed for a specific frequency band to achieve impedance matching and sufficient harmonic suppression. Receivers could be possibly multi-band, but I didn't see any yet.

Most used SAW resonators with clearly marked frequency and many no longer active due to reliability issues with temperature etc.

I am attaching photo of my reciever module. Their is a sticker on it which specifies 3 frequencies. I think by seeing it the seller thought it supports all 3.