HF+ bandwidth issue?


Dave GW4GTE
 

Hi
Can anyone else replicate this / comment?
Conditions:
HF+, Airspy 1631, sampling bandwidth 768kHz, signal bandwidth anything, no connection to either sma antenna port.
Adjust range to reveal noise floor at about -105dB

I'm finding that there is a 'carrier like' signal just alongside the signal passband, and as you change frequency this 'carrier' momentarily peaks then drops back. at lower frequencies (a few MHz) it's zero or almost zero, but at say 30 MHz the momentary peak is over 20dB.
Moving up to VHF, on say 144 MHz, the spike is settling at about 15dB above the noise floor. Reminds me of the centre DC /noise spike in direct conversion SDRs of old.

Now the interesting bit:
This also happens at a sampling bandwidth of 384k, but at 192k and below it appears to disappear completely (at least as far as I have investigated this)

I will post some HF+ tests on here versus other stuff I have  like Perseus, 7300 and Colibri Nano, but for now, the -140dBm MDS seems to be just about right (stretching MDS to the limit) on HF, and maybe 6 or more dB better on VHF. Compared to the Perseus on HF, the HF+ is about 6-8 dB more sensitive. 140 dBm may sound amazing , but '@ 500Hz bw' and 'MDS' (discuss) are a clue. 

Still, it's an amazing achievement for the price, and the quality of the unit is first class, as is the packaging. Sort of Apple-like.

Dave GW4GTE


prog
 

On Sat, Jan 6, 2018 at 03:13 am, Dave GW4GTE wrote:
Hi
Can anyone else replicate this / comment?
Conditions:
HF+, Airspy 1631, sampling bandwidth 768kHz, signal bandwidth anything, no connection to either sma antenna port.
Adjust range to reveal noise floor at about -105dB

I'm finding that there is a 'carrier like' signal just alongside the signal passband, and as you change frequency this 'carrier' momentarily peaks then drops back. at lower frequencies (a few MHz) it's zero or almost zero, but at say 30 MHz the momentary peak is over 20dB.
Moving up to VHF, on say 144 MHz, the spike is settling at about 15dB above the noise floor. Reminds me of the centre DC /noise spike in direct conversion SDRs of old.

Now the interesting bit:
This also happens at a sampling bandwidth of 384k, but at 192k and below it appears to disappear completely (at least as far as I have investigated this)

I will post some HF+ tests on here versus other stuff I have  like Perseus, 7300 and Colibri Nano, but for now, the -140dBm MDS seems to be just about right (stretching MDS to the limit) on HF, and maybe 6 or more dB better on VHF. Compared to the Perseus on HF, the HF+ is about 6-8 dB more sensitive. 140 dBm may sound amazing , but '@ 500Hz bw' and 'MDS' (discuss) are a clue. 

Still, it's an amazing achievement for the price, and the quality of the unit is first class, as is the packaging. Sort of Apple-like.

Dave GW4GTE
Thanks for the tests and the kind words. The receiver operates in Low-IF mode at sample rates <= 192ksps and Zero-IF mode for higher sample rates (384 and 768 ksps. The image rejection uses a state of the art algorithm with rejection exceeding the actual dynamic range of the front end.


Alberto I2PHD
 

On 1/6/2018 12:13 PM, Dave GW4GTE wrote:

the quality of the unit is first class, as is the packaging. Sort of Apple-like.

Are you sure that is a positive remark for the HF+ ? Many (me included...)
despise Apple and all of their products...

--
73 Alberto I2PHD
Credo Ut Intelligam



jdow
 

On 2018-01-06 03:31, Alberto I2PHD wrote:
On 1/6/2018 12:13 PM, Dave GW4GTE wrote:

the quality of the unit is first class, as is the packaging. Sort of Apple-like.
Are you sure that is a positive remark for the HF+ ? Many (me included...)
despise Apple and all of their products...
--
/*73 Alberto I2PHD*
Credo Ut Intelligam/
I respect them for the design that goes into them. The basic problem is that they are designed for a different part of the human race than the part into which I fit. I simply get frustrated trying to make them do even simple things. They require I think wrong and consider alt-meta-coke-bottle-milk-bottle mouse button press as being intuitive or something. At least windows is almost sane. I imprinted on AmigaDOS, though. It has some REALLY nice features. One I really liked was right click and hold to bring up menu, left click to select multiple items, let up right button. Then the things are done in selected order. It's sort of a macro feature for menus. Now THAT's efficient for driving a computer without getting in your face retracing the same menu three or four times.

Hm, Classic Shell is open source now. I wonder if I could plant some of that feature into the system somehow. I suspect not; but, it's worth looking at.

{^_^}


Roberto Zinelli
 

Albert  not for me, as ex microsoft system administrator i like apple products, ...
and linux S.O is in my house so as in the ISS.. all depends on the experiences.

Inviato da OldPhone

Il giorno 06 gen 2018, alle ore 12:31, Alberto I2PHD <i2phd@...> ha scritto:

On 1/6/2018 12:13 PM, Dave GW4GTE wrote:

the quality of the unit is first class, as is the packaging. Sort of Apple-like.

Are you sure that is a positive remark for the HF+ ? Many (me included...)
despise Apple and all of their products...

--
73 Alberto I2PHD
Credo Ut Intelligam



Alberto I2PHD
 

On 1/6/2018 2:17 PM, Roberto Zinelli wrote:

Albert  not for me, as ex microsoft system administrator i like apple products, ...
and linux S.O is in my house so as in the ISS.. all depends on the experiences.

Roberto, while this is not the right place to discuss this kind of arguments, let me
say that despite being I a long term Windows user, I embraced recently also Linux,
and I am currently programming in Linux to develop something SDR-related for that
little board that is the Raspberry Pi 3B.

That said, I will never lower my deflector shields, forcing myself to wear a straitjacket
which is the prerequisite to be able to work in the Apple environment, which can be
summarized as :

"I only need two things. Your submission and your obedience to MY WILL!"

--
73 Alberto I2PHD
Credo Ut Intelligam



paul
 
Edited

"Are you sure that is a positive remark for the HF+ ? Many (me included...)
despise Apple and all of their products..."

Mmm. Have been using my iPad One for over 8 years now almost every day.
It is still flawless and like brandnew. I plan to bring it to its 10 year anniversary.

Same for my 2 iPods ( a Nano and a Classic) , several Mac Pros and Mac Minis.
Never had a security issue, never a hardware failure.
Not one.

Most Apple hardware I ever purchased is still in use somewhere, without any issue or frustration.

I think the frustration mostly lies in developers not being able to meet Apple's quality&stability demands.

Would be looking forward to a OS-X SpyServer client from Chris Smolinski @ Black Cat Systems!

73
Paul



Dave GW4GTE
 

Hi Alberto,
I stand by what I said, in the context it was said within. Apple have managed to create a brand image of quality high end (and high priced) products (albeit more and more contenders for the crown these days). The comment does not state or imply that I or others endorse other aspects of Apple's business. Indeed I too dislike Apple's all controlling  business model. And iTunes!  All the more annoying when they appear to have demonstrated that it pays off!

Having said that, I own an iPad Air and an iPhone 6, and the things 'just work' dammit! :-)

As others have commented, opinions differ. Vive la difference! As it were.

Dave GW4GTE


Dave GW4GTE
 

Thanks Youssef,

That explains my observations. I think I read somewhere about the low-IF / Zero IF now you mention it. Even though the noise floor reveals the remnants in the lab, back in the real world, on a real antenna, if I ever saw it I'd congratulate myself on having such a supremely quiet receive site!
Dave


mike
 

On 6 Jan 2018 at 8:29, Dave GW4GTE wrote:

Having said that, I own an iPad Air and an iPhone 6, and the things 'just
work'
They are sooo annoying <vbg>
Iphone 4 with dead battery free to good home. UK Only.
73 Mike
( HF+ arrived this am, no hassles, working beautifully)


Greg Whynott
 



On Sat, Jan 6, 2018 at 6:31 AM, Alberto I2PHD <i2phd@...> wrote:
On 1/6/2018 12:13 PM, Dave GW4GTE wrote:

the quality of the unit is first class, as is the packaging. Sort of Apple-like.

Are you sure that is a positive remark for the HF+ ? Many (me included...)
despise Apple and all of their products...


No trolling please.  This is beyond old.  Keep it on topic.  Its the internet not everyone agrees but the point was obvious.





jdow
 

I put it this way when addressing the MS and Apple boys, "Just who do you think owns this computer I bought and paid for? It's MY toy/tool, not your money siphon into my bank account."

{^_^}

On 2018-01-06 07:55, Alberto I2PHD wrote:
On 1/6/2018 2:17 PM, Roberto Zinelli wrote:

/Albert  not for me, as ex microsoft system administrator i like apple products, .../
/and linux S.O is in my house so as in the ISS.. all depends on the experiences./
Roberto, while this is not the right place to discuss this kind of arguments, let me
say that despite being I a long term Windows user, I embraced recently also Linux,
and I am currently programming in Linux to develop something SDR-related for that
little board that is the Raspberry Pi 3B.
That said, I will never lower my deflector shields, forcing myself to wear a straitjacket
which is the prerequisite to be able to work in the Apple environment, which can be
summarized as :
*"I only need two things. Your submission and yourobedienceto MY WILL!"
*
--
/*73 Alberto I2PHD*
Credo Ut Intelligam/


jdow
 

I've solved the iTunes problem. I use an RTL dongle with SDRSharp, an admittedly very old version I tweaked to fix the favored station's bug. It's stuck on KUSC and sits there 24/7 listening to the kind of music I prefer. It even has its own audio dongle for output to an external mixer. It uses about four to six percent of the machine it's on. And I need iTunes, why?

I do need a new phone, though. My ancient Motorola E815 flip phone is on it's last legs. I've not really figured out yet why having a cell phone is mandatory. So I consider it optional at best. I'll have to figure out what to get. I seem to have an Apple allergy, can't make Mac's work to save my life. And with the Korea mess I keep wondering how long a Samsung phone might live....

{^_-}

On 2018-01-06 08:29, Dave GW4GTE wrote:
Hi Alberto,
I stand by what I said, in the context it was said within. Apple have managed to create a brand image of quality high end (and high priced) products (albeit more and more contenders for the crown these days). The comment does not state or imply that I or others endorse other aspects of Apple's business. Indeed I too dislike Apple's all controlling  business model. And iTunes!  All the more annoying when they appear to have demonstrated that it pays off!
Having said that, I own an iPad Air and an iPhone 6, and the things 'just work' dammit! :-)
As others have commented, opinions differ. Vive la difference! As it were.
Dave GW4GTE


Dave GW4GTE
 

I too fixed the iTunes problem. I use Spotify.