Help understanding Disco 1 alarm system

Hi all,
I have a 1998 300tdi Disco which I am slowly bringing life back too after being neglected and "improved" by a previous owner. I'm wanting to understand more about the alarm/immobilizer system.
I have read through the RAVE manual and still aren't 100% sure on how it works.

Basically want to know, is it possible to lock and unlock the vehicle with just the key or must it be unlocked with the FOB? I understand that locking with the key will not activate the full protection (perimetric only), but in one sentence it says the FOB must be used to deactivate the alarm and mobilize the vehicle but the next sentence says the passive coil will re-mobilize it also.

So along with that, what purpose does the passive coil serve?
I have driven the vehicle with it being connected and then disconnected, doesn't seem to make a difference. With it connected I tried to unlock using the key and tried starting (with FOB close to passive coil), but upon opening the door the alarm sets off and the vehicle wont start.

The last owner appears to have removed the ultrasonic sensor and I have installed the spyder bypass, if either of these are factors.

Thanks

For a better understanding of the operating principle of Thatcham vehicle security systems similar to what is fitted to the 300 series disco... just Google.

NO. The alarm needs to be deactivated (unset) before unlocking with central locking.
Using the fob also remobilise the engine for a short period, so open the door get in, start the engine and a way u go, when that period has lapsed the system, as its passive, will immobilise the engine so then u need to place the fob near the coil to remobilise the engine or press the unlock button on the fob but that's not applicable to u if you have fitted a spider bypass.

Unlocking the door with a key does no unset the the alarm, and it will sound as u have found out, pressing the lock button on on the fob will silence the alarm.

Thanks for the reply.
That makes sense now, I'll have to plug the passive coil back in and make sure it works.

So the only way you can unset the alarm is using the FOB or the EKA code.
Shame I have no idea what the EKA code is, is a Landrover dealer the only place that can find out my EKA code?

The EKA code is the "Emergency Key Access" code. I know that on the D2, it can be found using a code reader such as a Nanocom, I'm not sure about what code readers are usable on the D1, but the EKA might be available. However, you'll probably have to cancel the alarm before the code reader will communicate successfully with the vehicle.
Provided that a previous user has not changed the EKA, LR might be able to provide you with the original EKA, but there's the age problem to deal with now and whether LR actually keep on file information from that far back. If they do, you'll obviously need to provide proof of ownership before they'll give it to you.
Exactly how to use the EKA is shown in the Owner's Handbook, but I've attached it below:

Thanks again, I'll try contacting a local LR dealer and see if they can sort out an EKA code and the programming of another FOB (I currently have no back up and no EKA!), failing that I'll try the remotekey guys.

Cheers