Eric Swartz WA6HHQ, co-founder of Elecraft, joins us to guide our understanding of RF receiver performance specifications. Eric introduces us to common receiver specs such as Sensitivity, Noise Floor, Dynamic Range, Intermod Dynamic Range, Phase Noise, and RMDR. He tells us what they mean in real-world receiver performance terms, how they are tested, and whether it’s better to have a higher or lower number in each one. It’s also the final episode before the 2018 Hamvention and George and Jeremy share our plans for our Booth, special offers, and exclusives for show listeners who stop by booth 3104 in Xenia.

Show Topic Begins at 1:09:36

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Want to be on the show? Come to the booth and tell us what’s on your workbench!

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Visit Digilent at booth 3002

QRP ARCI - Four Days in May - http://www.qrparci.org/fdim

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Arduino Projects for Amateur Radio - https://www.amazon.com/Arduino-Projects-Amateur-Radio-Purdum/dp/0071834052

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Sam Zeloff - Garage Chip Fab

https://hackaday.com/2017/02/25/the-fab-lab-next-door-diy-semiconductors/

https://hackaday.com/2018/04/24/first-lithographically-produced-home-made-ic-announced/

https://hackaday.com/2018/05/03/more-details-on-that-first-home-made-lithographically-produced-ic/

Amp Hour Interview with Sam - https://theamphour.com/390-an-interview-with-sam-zeloof/

Sam Zeloff Youtube Channel - https://www.youtube.com/channel/UC7E8-0Ou69hwScPW1_fQApA

Bletchley Park - https://bletchleypark.org.uk/

Update on George’s Projects on his blog - http://www.kj6vu.com/

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USB In-Line Multimeter - https://www.amazon.com/Eversame-Multimeter-Chargers-Capacity-Banks-Black/dp/B01D9Y6ZFW/ref=sr_1_3?ie=UTF8&qid=1525531260&sr=8-3&keywords=usb+meter

Randy K7AGE YouTube channel - https://www.youtube.com/user/K7AGE

Eric 4ZIUG QSO Today Podcast - https://www.qsotoday.com/

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IKEA Algot Shelving - https://www.ikea.com/us/en/catalog/categories/departments/bedroom/22798/

IKEA Bekant Desk - https://www.ikea.com/us/en/catalog/products/S09022804/#/S19022808

RF Receiver Specifications Guide from Eric Swartz WA6HHQ

Elecraft Mailing List - http://www.elecraft.com/elist.html

Sensitivity - How well can the receiver hear weak signals?

Minimum Discernible Signals - noise is generated inside the radio from the amplifier stages and how much amplification is available in the receive chain to bring a signal above the radio’s internal noise floor
As sensitivity increases, you can degrade dynamic range
To measure, start by injecting weak signals until you observe the signal level out of the speaker roughly double in amplitude (3dB)
Lower values are better (bigger negative number), allowing you to detect weaker signals
Most HF radios are between -125 to -130 with -135 to -138 being on the higher side of performance

Noise Floor

The internal noise figure generated by the radio with the antenna removed

Dynamic Range

Strong Signal Handling - how does the radio perform when there are strong signals adjacent to where you are tuned?
IMDR3 - Intermodulation Dynamic Range
When multiple strong received signals overload the first receiving amplifier in your radio, the signals get clipped
When the radio has a broad banded receiver, this clipping begins to act as a mixer and creates intermodulation showing up at different frequencies
Additional unwanted signals are created in the receiver when multiple strong signals are present
To measure, begin with two signals apart - the difference between the MDS/sensitivity and the level required to set the signal generator to to cover up the weak signal
Higher values are better - 90dB range above noise floor is average, mid 90’s to 100 dB is on the higher side of performance

Blocking Dynamic Range

A strong signal overloading your receiver thereby reducing the gain of the receiver.
Receivers can have challenges when a strong signal is physically near the radio
To measure, inject a signal until it causes receiver overall gain to drop one DB
Higher values are better - typical better than 130dB of BDR, mid 130s to 140s is on the higher side of performance

Phase Noise

An indication of the quality and “cleanliness” of local oscilator (VFO, or Crystal Master Oscillator)
Denotes whether they introduce jitter or noise to the received signal
Lower is better

Reciprocal Mixing Dynamic Range (RMDR)

RMDR is tied to phase noise
Impacted by how clean your oscillator is
To measure, listen in 500hz bandwidth and measure how strong an injected signal has to be to raise the noise floor on the freq you are tuned to (1-3dB noise floor increase)
This ratio is the RMDR
Higher values are better - 110-115 dB
As multiple signals get closer, the RMDR drops

Sherwood Engineering Receiver Comparison List - http://www.sherweng.com/table.html

HRWB049-Understanding RF Receiver Specifications 02:32:24 Share

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HRWB049-Understanding RF Receiver Specifications