not really about what is happening....
what specifically is causing the jamming the door transmitter ?
what specifically do you mean by jamming ?
is the DSC 433 MHz receiver actually being used to receive the signal from the door transmitter?
if not what are the DSC 433 MHz receivers being used for ?
if the DSC 433 MHz receivers are being used for other projects and not related to the door system then it just shows that they are on the same freq.
433MHz is a standard LIPD freq ( LIPD = Low Intereference Potential Device) as in low intereference to other services like commercial and amateur radio services.
Unfortunately they are anuthing but low intereference, they cause horrific problems that I have to deal with every time I turn on my radio gear.
can you just explain a little clearer what is occurring, answer the above Q's and see if we can get you on the right track