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Hi, dear all,

I try to use garp1 sequence for decoupling with the statement " obsprgon("garp1", pw, angle, 0) ".

If angle = 1.0, when pw = 4us or larger than 4us, the sequence works. When pw less that 4us, it shows the error "effective dmf too high prg dec on on controller dec".

If angle = 2.0, when pw = 2us or larger than 2us, it works. When pw less that 2us, the it shows the same error message.

Hope for your help!

asked Jun 27 '11 at 03:37

Frey's gravatar image


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I am not sure what you're trying to accomplish, but a pw of 2-4 us doesn't sound correct to me... A pulse of 4 us would correspond to ~12.5 kHz field; garp1 decouples properly over 2.5 times this value (see for example the book of Cavanagh, p. 204-209). If you are using garp1 as decoupling sequence then the "tip_angle resolution" should be equal to 1.0 (see the Varian command and reference parameter book or look in the .DEC file); so there is no point in putting this at 2.0

You should figure out over what field strength you need to decouple the proton range (at least I assume that's what you're trying to do?), then get determine at which power you need to apply the garp1 sequence and determine the pw at this field. Also, in your sequence make sure that you actually change the power to the appropriate level; you do not want to do decoupling at full power!

Just my thoughts... explaining a bit more what you're trying to do (are we talking about solution state NMR, protein, etctera) might help.


answered Jun 29 '11 at 12:17

renee's gravatar image


updated Jun 29 '11 at 12:21

Hi,Renee, I use obsprgon("garp1", pw, angle, 0) for decoupling with several milliseconds. Typically, the garp1 should have empirical bandwidth and power. But I want to use it with any power and any pw value. What puzzled me is the relation between 'pw' and 'angle'. - Frey (Jun 30 '11 at 06:14)

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