There seems to be an increase in the transmit bandwidth range for SSB communications, which traditionally operates within a narrow-band of approximately 3 kHz. Now if we go with a 3 khz “Voice channel” for Single Side Band (SSB) then the Transmitted Bandwidth, let's call it the TxBW, should fit into the range 0-3000 kHz.
However, I’ve noticed more and more operators use a TxBW of 4 kHz or more. This is often referred to as Extended Single Side Band (ESSB) which I have seen to extend in some instances even to 5 kHz and more. The claim to fame is HiFi Audio.
Now Amateur Radio is an experimental hobby, so this, on the surface, shouldn’t irk anyone, shouldn’t it? However, I frequently encounter ESSB operators on 20 and 40m talking to operators who have not modified their station for ESSB communications, i.e. a station with a TxBW 5 kHz to a station with a 3 kHz Receiver Bandwidth, lets call that RxBW.
So what seems to be the issue?
Let's say a QSO is conducted on 14.229 MHz, on operator uses a TxBW of 2.9 khz and the other uses a TxBW of 2.4 kHz. Signal are good with about S7 both ways. Since this is conducted using the Upper Side Band and, if we apply a Voice Channel spectrum of 3 kHz the used frequency spectrum for that QSO is from 14.229 – 14.231 MHz (not quite but let's stick with 3 kHz).
If we have an ESSB operator calling “CQ DX” on 14.225 MHz using a TxBW of 5 kHz his/her use of the frequency spectrum is 14.225 – 14.300 MHz.
Anyone see the issue here? Well, I do! I can see a clear issue here but, does the ESSB operator see the issue? From my experience the operator does not.
My question is why use 5 kHz in conducting DX contacts. Aren't we trying to share the limited frequency spectrum between all Amateurs? There is NO benefit to the station receiving the ESSB station.
Frequency spectrum during “openings” are crowded and transmitting with a 5 kHz ESSB TxBW during these opening does not show any courteousey towards other spectrum users.
The above shows an Australian Operator transmission with a TxBW of 5 kHz and the DX station using a less than 3 kHz “Voice Channel”. I will assume that the DX stations RxBW would not be more than it's TxBW.
NOTE: I’m referring to the TxBW and not the Intermodulation Products (IM) or “splatter”, i.e. the light blue “hair or whiskers” on either side of the signal, which are obvious related but are not discussed here.
On 40m I’ve noticed similar issues arising from the use of excessive TxBW using ESSB to conduct local rag-chewing throughout our limited frequency spectrum. Assume the ESSB operator is transmitting on 7.150 MHz using Lower Side Band (LSB) with a 5 kHz TxBW. His/her signal would be from 7.150 – 7.145 MHz. Lets assume that a DX station is utilising the 7.146 MHz frequency and is being heard by a local stations. What is the situation here?
Can the local operator, which hears the DX station answer the CQ DX call?
Well, in theory the operator would interfere with the ESSB station and as soon as the ESSB station starts to transmit the local operator would lose the ability to hear the DX station.
Now Amateur Radio is an experimental hobby and experimenting with a TxBW > 3 kHz does fall under this category. So, yes I believe in experimenting but this is not experimenting, this is not understanding the implication of excessive TxBW. And believe me I’m all for experimenting. I am quite happy with a 2.4 kHz well balanced audio TxBW and RxBW however, some tend to enjoy a poorer SNR with an Excessive Wide Single Side Band signal.
NOTE: I also observed that these type of operators seem to drop their TxBW to 3 kHz during Contests!?! Yet during crowded DX sessions it is OK to use 5 kHz or more TxBW. Isn't that a bit hypocritical.
I believe Amateur Radio is a self regulating hobby so maybe it is about time time to add a frequency spectrum for those inclined to use ESSB. I believe this has been done for certain other modulation schemes (AM/FM/DIGITAL).
