Monday, November 28, 2016

5T9VB Mauritania and Changes in Flex's Filtering Scheme vs APF

I was listening to 30M and heard 5T9VB in Mauritania on the west coast of Africa.  The terminator was about half way between us on a 4130 mile path

My band noise was near -117 dBm and he was peaking -114sBm or a little better with some QSB.  I managed to work him in 2 calls.  I've recently been involved in a conversation with Bjorn LI9IAA regarding the Flex 6K series vs the Anan radios in terms of feature set.  The radios share some homology but in some respects the Anan in my opinion at least when using HPSDR is more of a variant of the Flex 5K rather than something akin to the 6000 series.  To be sure the Anan/HPSDR is different than the F5K but I think it's implementation is more of a refinement of a 5K.  I own both Flex and Anan and have a 5K, a 6300, a 6500 and a 6700 as well as a Anan 10.  I had a 100D but decided to sell that radio.  

Given the strength of 5T9VB at my QTH I thought it might be an ideal way to show how Flex is doing it's filtering.  I'm using version software.  Flex has implemented a filter matrix that allows latency vs filter sharpness to be chosen depending on need and preference

Sharp filters have best S/N and QRM rejection whereas filters with less steep skirts have lower latency.  Latency becomes important to operators who demand pristine QSK, whereas sharp skirts are important to those of us that require best S/N.  The matrix allows you to tune your radio to your given or perceived needs.  My needs are best S/N.  I find QSK to be absolutely unimportant.  If I want it it is available to me and I even have full duplex available if I want it.  

I made a video of how the matrix works at various bandwidths and I added APF since Bjorn was interested in how APF works in the Flex.


73  W9OY