Airspy HF+


Larry Dighera <larry@...>
 

I queried two of the foremost amateur radio reviewers about the new Airspy
HF+. Here are their responses:

From: Rob Sherwood. [mailto:rob@...]
Sent: 19 July, 2017 12:28
To: Larry@...; farson@...
Cc: sdrsharp@...
Subject: RE: Airspy HF+

Hi Larry,

Just a couple of comments. IP3 is a meaningless number for a direct
sampling radio. I also don't understand the meaning of "image rejection" as
applied to a DS SDR.

There must be quite a bit of preamp and/or ADC driver gain to push the noise
floor down to the levels quoted. What is the ADC overload value in dBm for
any preamp settings?

What is the phase noise at 10, 20 and 100 kHz on 20 meters? That is likely
more important than at 1 kHz offset where in reality if listening to a weak
CW signal next to a very strong CW signal, the adjacent signal's key clicks
will dominate before phase noise.

Is there an RMDR spec for the receiver at 2 and 20 kHz, as is now usually
quoted in any review in QST?
One would expect the RMDR value to be HF ham band independent.

When I was writing for Passport to Worldband Radio for its 25 years of its
existence as their laboratory, receivers as opposed to transceivers would
have been of prime importance. Today with a significant drop in shortwave
broadcasting, I don't think the shortwave market is a shadow of its former
self.

On the other hand, SDR dongles are being used for spectrum scope for
transceivers missing this feature, and for CW Skimmer and reverse beacon
reception.

At present with new product announced at the Dayton Hamvention, I am only
planning to test DS SDR transceivers this year. Examples: Icom IC-7610,
Flex 6600M, Apache ANAN 8000DLE, and a second and possibly a third sample of
the Elecraft KX2. I have the second KX2 here now in my possession as of
last evening.

Adam may have more time than I for testing receiver only products, as I am
still working part time with a sub set of my IT client base, at least for a
few more years.

73,
Rob Sherwood
NC0B
-------------------------------

From: Adam Farson [mailto:farson@...]
Sent: 19 July, 2017 13:45
To: 'Rob Sherwood.'
Subject: RE: Airspy HF+

Rob, Larry,

Just looked over the Airspy HF+ web page. Firstly, a look at the block
diagram tells me that this is a superhet receiver, with analogue mixers and
LO's for HF and the two upper bands feeding IF's into an ADC. Hence the
"image rejection" term is relevant. (As an aside, the non-native English
writing style of the website is a little weird.)

No RMDR value is stated, but the specified 100 MHz phase noise value does
not look too good when expressed as RMDR.

"Very low phase noise PLL (-110 dBc/Hz @ 1kHz separation @ 100 MHz)".
Assuming B = 500 Hz, this resolves to 83 dB RMDR - less than stellar by any
account.

The device appears to have a varactor-tuned tracking preselector. Due to
parametric effects in the varactors under strong-signal conditions, this can
be a horrendous IMD generator, as we saw with the early JRC receivers and
transceivers.

Rob, I agree completely with your comments regarding receivers vs.
transceivers and the uses to which dongles are put. For HF and 6m, I believe
that the Russian Colibri Nano is a much more interesting device than the
Airspy. It is a 14-bit direct-sampler. Here is my Nano test report:

http://www.ab4oj.com/sdr/sunsdr/nano_notes.pdf

I am more than willing to test serious contenders in the receiver world. For
example, Icom Canada will loan me an R-8600 for testing, probably next
month. I am no longer motivated to test any purely legacy architecture;
although I am retired and have more available time, I do have a life outside
my little 6.5m2 lab.

73, Adam VA7OJ/AB4OJ

-----Original Message-----
From: Larry Dighera [mailto:Larry@...]
Sent: Wednesday, July 19, 2017 9:55 AM
To: Rob Sherwood. <rob@...>; farson@...
Cc: sdrsharp@...
Subject: Airspy HF+

Gentlemen,

I'd be interested in your opinions on this new entry into the SDR market, as
I'm sure many others would be also.

Technical specifications

HF coverage between DC .. 31 MHz
VHF coverage between 60 .. 260 MHz
-138 dBm MDS at 500Hz bandwidth in HF
-142 dBm MDS at 500Hz bandwidth in VHF
+26 dBm IIP3 on HF at maximum gain
+13 dBm IIP3 on VHF at maximum gain
110 dB dynamic range in HF
95 dB dynamic range in VHF
120 dB Image Rejection
0.1 dB Spectrum Flatness
0.5 ppm high precision, low phase noise clock
660 kHz alias and image free output
18 bit Digital Down Converter (DDC)
+10 dBm Maximum RF input
Very low phase noise PLL (-110 dBc/Hz @ 1kHz separation @ 100 MHz)
2 x High Dynamic Range Sigma Delta ADCs @ up to 36 MSPS No Silicon RF switch
to introduce IMD in the HF path Routable RF inputs Wide Band RF filter bank
Tracking RF filters Sharp IF filters Smart AGC with real time optimization
of the gain distribution All RF inputs are matched to 50 ohms
4 x Programmable GPIO's
No drivers required! 100% Plug-and-play on Windows Vista, Seven, 8, 8.1 and
10
Industrial Operating Temperature: -45°C to 85°C

Best regards,
Larry
WB6BBB

============================================================================
http://airspy.com/airspy-hf-plus/
Airspy HF+ (Coming soon)
You are here: HomeAirspy HF+ (Coming soon) Description

The Software Defined Radio revolution brought great flexibility in VHF and
UHF reception. Today we offer the best wide band receivers which address
these needs. We also provide a high performance extension for weak-signal
wide band reception on HF - something other competing solutions in our price
segment fail to address efficiently.
Airspy HF+ is a paradigm shift in high performance HF radio design. It is a
joint effort between Airspy, Itead Studio and some famous chip maker to
build a state of the art SDR for HF and VHF bands.
Like most high-end HF receivers, the HF+ uses very high dynamic range ADC's
and front-ends. But unlike the current offerings in the market, it also
brings more frequency agility by using high performance passive mixers with
an excellent overtone rejection structure. No external band aid filters are
required like the lower end HF receivers, which makes it the ideal companion
for light portable high performance operation.
Both the architecture and level of integration achieved in this design allow
us to bring top performance reception at a very affordable price.

All the major SDR software is supported. Check the download page.

We concentrated state of the art DSP and networking techniques into our
SpyServer software to allow multiple users to stream high quality IQ data
from the same receiver at the same time. No compromises in the quality were
made like it is usually done in Web SDR interfaces. You get actual IQ data
you can process with your plugins and extract the last bit of information
out of it.

The server software is highly scalable and can run on computers as small as
the $7 Orange Pi Zero to top end 64bit servers with multiple cores/cpus,
passing by the popular Raspberry Pi series.

Airspy HF+ Cloud

Architecture

Airspy HF+ Architecture Diagram

HF Tuner

Airspy HF+ achieves excellent HF performance by mean of a low-loss band
filter, a high linearity LNA, a high linearity tunable RF filter, an
over-tone-rejection (OTR) mixer that rejects up to the 21st harmonic and an
IF filter.

The 6 dB-stepped AGC gain is fully controlled by the software running onto
the DSP which optimizes the gain distribution in real time for optimal
sensitivity and linearity. OTR is a key issue in wide band HF receivers
because of the large input signal bandwidth. The output of the IF-filter is
then digitalized by the IF ADC for further signal processing.

VHF Tuners

Excellent VHF performance is also achieved by using optimized signal paths
composed by band filters, high linearity LNAs with a stepped AGC and an
over-tone-rejection mixer and IF filters optimized for their respective
bands.

The amplifier gain is switchable in 3 dB-steps and is fully controlled by
the AGC processing running onto the DSP. The RF signal is converted to
baseband by a high linearity passive mixer with overtone-rejection
structure. The low-IF signal is then converted into the digital domain by
the IF ADC for further digital signal processing.

IF Digitalization

The IF digital to analog converter has a 4th order multi-bit topology; it
features very high dynamic range and linearity. The IF-ADC sampling
frequency is determined by a control algorithm running on the DSP. This
advanced technique changes the sampling frequency depending on the tuning
frequency with the goal of avoiding the disturbances generated by the
switching discrete-time sections of the IF-ADC.

Digital Down Converter

Once the IF signal is digitalized, the high sample rate I/Q stream is then
frequency translated and processed with cascaded CIC and FIR decimation
stages. After every stage, the sample rate is reduced and more the
resolution is increased. The final signal at the output has 18bit resolution
and the alias rejection performance is 108 dBc. The data is then scaled to
16bit and sent to the Micro-Controller for streaming over USB.

Use it over the network!

Connect as many SDR applications as needed to the HF+, over the Internet or
in your own local network with near zero latency thanks to the new SPY
Server software.

This setup basically brings all the flexibility of Web based SDRs while
still benefiting from the full power of desktop applications. The IQ data is
processed in the server with state of the art DSP and only the required
chunk of spectrum is sent over the network. What is sent is the actual IQ
signal, not compressed audio. This means you can use all your favorite
plugins to process the IF, eliminate noise and perform heavy lifting of the
signals as you are used to do with locally connected SDR's.

We have a tradition of building multi-tools, so we made sure the SPY Server
runs on 32/64bit Windows and Linux on Intel and ARM processors without any
compromises. Low cost Raspberry Pi 3 and Odroid boards are in the party.

Technical specifications

HF coverage between DC .. 31 MHz
VHF coverage between 60 .. 260 MHz
-138 dBm MDS at 500Hz bandwidth in HF
-142 dBm MDS at 500Hz bandwidth in VHF
+26 dBm IIP3 on HF at maximum gain
+13 dBm IIP3 on VHF at maximum gain
110 dB dynamic range in HF
95 dB dynamic range in VHF
120 dB Image Rejection
0.1 dB Spectrum Flatness
0.5 ppm high precision, low phase noise clock
660 kHz alias and image free output
18 bit Digital Down Converter (DDC)
+10 dBm Maximum RF input
Very low phase noise PLL (-110 dBc/Hz @ 1kHz separation @ 100 MHz)
2 x High Dynamic Range Sigma Delta ADCs @ up to 36 MSPS No Silicon RF switch
to introduce IMD in the HF path Routable RF inputs Wide Band RF filter bank
Tracking RF filters Sharp IF filters Smart AGC with real time optimization
of the gain distribution All RF inputs are matched to 50 ohms
4 x Programmable GPIO's
No drivers required! 100% Plug-and-play on Windows Vista, Seven, 8, 8.1 and
10
Industrial Operating Temperature: -45°C to 85°C Typical Applications

High Performance Networked HF/VHF Radio
Ham Radio (HF + 2m)
Short Wave Listening (SWL)
AM DX
FM DX
VHF-L TV DX
Remote Telemetry Radio Receiver
Low Bands IoT
Supported platforms

Windows Vista, 7, 8, 8.1 and 10 (For Windows XP, please contact us) Linux
*BSD OSX Minimum hardware requirements

1GHz Pentium or ARM
1GB of RAM (to run your own OS, HF+ barely needs 1MB of memory) High speed
USB 2.0 controller Supported Software

Check the download page
Developer API

Open source, multi-platform user mode driver libairspyhf on github



On Fri, 28 Jul 2017 09:04:35 +0100, "'Simon Brown' simon@...
[sdr-radio-com]" <sdr-radio-com@...> wrote:

So,

A lucky person has a HF+ and has been using it in the wild:
https://twitter.com/rtlsdrblog/status/890770679255060480

Simon Brown, G4ELI
www.sdr-radio.com

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