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10. Filtering (From version 1.45)

10.1 General filter rules

Upto v1.44 it was not possible for the user to set their own filters. From v1.45 though that has all changed. It is now possible to set filters for just about anything you wish. If you have just updated from an older version of DXSpider you will need to update your new filters. You do not need to do anything with your old filters, they will be renamed as you update.

There are 3 basic commands involved in setting and manipulating filters. These are accept, reject and clear. First we will look generally at filtering. There are a number of things you can filter in the DXSpider system. They all use the same general mechanism.

In general terms you can create a 'reject' or an 'accept' filter which can have up to 10 lines in it. You do this using, for example ...

accept/spots .....
reject/spots .....

where ..... are the specific commands for that type of filter. There are filters for spots, wwv, announce, wcy and (for sysops) connects. See each different accept or reject command reference for more details.

There is also a command to clear out one or more lines in a filter. They are ...

clear/spots 1
clear/spots all

There is clear/xxxx command for each type of filter.

and you can check that your filters have worked by the command ...


For now we are going to use spots for the examples, but you can apply the same principles to all types of filter.

10.2 Types of filter

There are two main types of filter, accept or reject. You can use either to achieve the result you want dependent on your own preference and which is more simple to do. It is pointless writing 8 lines of reject filters when 1 accept filter would do the same thing! Each filter has 10 lines (of any length) which are tried in order. If a line matches then the action you have specified is taken (ie reject means ignore it and accept means take it)

If you specify reject filters, then any lines that arrive that match the filter will be dumped but all else will be accepted. If you use an accept filter, then ONLY the lines in the filter will be accepted and all else will be dumped. For example if you have a single line accept filter ...

accept/spots on vhf and (by_zone 14,15,16 or call_zone 14,15,16)

then you will ONLY get VHF spots from or to CQ zones 14, 15 and 16.

If you set a reject filter like this ...

reject/spots on hf/cw

Then you will get everything EXCEPT HF CW spots. You could make this single filter even more flexible. For example, if you are interested in IOTA and will work it even on CW even though normally you are not interested in CW, then you could say ...

reject/spots on hf/cw and not info iota

But in that case you might only be interested in iota and say:-

accept/spots not on hf/cw or info iota

which achieves exactly the same thing. You should choose one or the other until you are comfortable with the way it works. You can mix them if you wish (actually you can have an accept AND a reject on the same line) but don't attempt this until you are sure you know what you are doing!

You can arrange your filter lines into logical units, either for your own understanding or simply convenience. Here is an example ...

reject/spots 1 on hf/cw
reject/spots 2 on 50000/1400000 not (by_zone 14,15,16 or call_zone 14,15,16)  

What this does is to ignore all HF CW spots and also rejects any spots on VHF which don't either originate or spot someone in Europe.

This is an example where you would use a line number (1 and 2 in this case), if you leave the digit out, the system assumes '1'. Digits '0'-'9' are available. This make it easier to see just what filters you have set. It also makes it more simple to remove individual filters, during a contest for example.

You will notice in the above example that the second line has brackets. Look at the line logically. You can see there are 2 separate sections to it. We are saying reject spots that are VHF or above APART from those in zones 14, 15 and 16 (either spotted there or originated there). If you did not have the brackets to separate the 2 sections, then Spider would read it logically from the front and see a different expression entirely ...

(on 50000/1400000 and by_zone 14,15,16) or call_zone 14,15,16 

The simple way to remember this is, if you use OR - use brackets. Whilst we are here CASE is not important. 'And BY_Zone' is just the same as 'and by_zone'.

As mentioned earlier, setting several filters can be more flexible than simply setting one complex one. Doing it in this way means that if you want to alter your filter you can just redefine or remove one or more lines of it or one line. For example ...

reject/spots 1 on hf/ssb

would redefine our earlier example, or

clear/spots 1

To remove all the filter lines in the spot filter ...

clear/spots all

10.3 Filter options

You can filter in several different ways. The options are listed in the various helpfiles for accept, reject and filter.

10.4 Advanced filtering

Once you are happy with the results you get, you may like to experiment.

The previous example that filters hf/cw spots and accepts vhf/uhf spots from EU can be written with a mixed filter, for example ...

rej/spot on hf/cw
acc/spot on 0/30000
acc/spot 2 on 50000/1400000 and (by_zone 14,15,16 or call_zone 14,15,16)

Note that the first filter has not been specified with a number. This will automatically be assumed to be number 1. In this case, we have said reject all HF spots in the CW section of the bands but accept all others at HF. Also accept anything in VHF and above spotted in or by operators in the zones 14, 15 and 16. Each filter slot actually has a 'reject' slot and an 'accept' slot. The reject slot is executed BEFORE the accept slot.

It was mentioned earlier that after a reject test that doesn't match, the default for following tests is 'accept', the reverse is true for 'accept'. In the example what happens is that the reject is executed first, any non hf/cw spot is passed to the accept line, which lets through everything else on HF. The next filter line lets through just VHF/UHF spots from EU.

10.5 A Filtering Tutorial

There is now an excellent primer/tutorial on filtering written by Jim Samuels, W3BG with an introduction by Dave Hawes N3RD that I strongly suggest you read. You can read it here The DXSpider User Filtering Primer

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