UADC™ series

UADC (Universal Analog to Digital Converter)  What is it:

Universal Analog to Digital Converter for Baseband (Zero-IF) Software Defined Radios

For many years Amateur Radio operators have used PC audio cards as an ADC, but PC Audio cards are for music and not for SDR applications. The absence of a proper ADC forced amateur operators to use audio cards with usable results nevertheless the improvement in RF Front-end designs was always limited by the PC audio cards. The UADC breaks this limiting factor and elevates the performance of properly ZERO-IF receivers to a new maximum of performance.  Cards with excellent performance such as the Delta-44 could be modified to improve their performance but then would go out of production. The UADC series hopes to eliminate the buy/modify cycle and offers a solution that will 'work out of the box'.


The trademark UADC4 is owned by Alex Artieda, HB9DRI.  Usage of "UADC4" for commercial purposes without written permission is strictly forbidden.. The UADC and UADC4 layouts are copyrighted as works of art and are the intellectual property, IP, of Alex Artieda;

The UADC4 is a multi-channel ADC which supports the UAC2 audio protocol. This protocol is supported by modern Linux, OS without drivers and Windows with a proprietary  external driver. The card has has 4 analog inputs to support 2 IQ pairs from 2 RF channels) and is able to sampling up to 192KHz,  Microsoft is currently developing a driver for USB audio for Windows 10 which should eliminate the need for the custom driver.

Performance:  ( verified by Leif Asbrink )

Associated with a ZERO IF mixer the UADC4 could deliver 15 to 20dB better performance than any other combo “IF mixer-sound card”. Never the less to reach the top performance better mixers are required. The initial performance test was done with 3 traditional receivers: the WSE converters from Leif SM5BSZ, the soft-rock receiver and the IQ+ from Alex HB9DRI.

In all cases the UADC4 deliver a minimum increase of performance around 10dB or more and the only reason we cannot reach another 10dB is because the “limiting factor” now is the Mixer and not any more the AD conversion.

In that way we observe a dramatically noise floor improvement, for example the WSE-Delta44 combo reach a -143dBc/Hz and -145dBc/Hz (@1KHz) when you modify the Delta44 sound card. Well the same WSE units running with the UADC4 reach an outstanding -163dBc/Hz @1KHz, a noise floor never ever reach by the WSE units using sound cards for AD conversion.

With the IQ+ we observe similar performance after some simple modifications on the IQ+ audio stage, the saturation point moves from -26dBm to -9dBm, that means the IQ+ with the UADC4 tolerate signals 17dBm stronger, that value doesn’t translate in 17dB more dynamic range because the LO in the IQ+ has a moderate phase noise, the final improvement result due reciprocal mixing is around 11dB but if we use a better local oscillator with less phase noise is possible to exploit the UADC4 to his maximum.

Different mixers will produce different results, for example a Softrock-UADC4 combo reach -45dB harmonic response when the WSE-UADC4 reach -70dB harmonic response and the reciprocal mixing noise floor is -156dBc/Hz @10KHz, this is 10dB better than the famous Perseus receiver.

What is really important to remark is the UADC4 open a new window of opportunity to associated better ZERO IF Mixers, in the past was not necessary to improve the Mixer performance because was the audio cards the limiting factor, with the dramatic improvement with the UADC4 the limiting factor moves now to the Mixer and Local oscillator, areas where is possible to develop better units.

For many years Leif Asbrtink, SM5BSZ, has been testing and comparing computer sound cards for use with SDR. His efforts has results in an extensive video library showing the performance of these cards with particular attention to specifications of interest to the Amateur Radio community.. This information has been collected in a single table ranking the relative performance of each card to other. an early version of the UADC4 was sent to Leif for testing. and the UADC4 results are shown in the table.

Prices and Ordering:

The UADC4 manufacturing, sales and fulfillment Is supported by Yoyodyne Consulting Inc. in Ontario, Canada.  Canadian HST or GST will be charged on Canadian orders. For other jurisdictions the customer will be responsible for import customs duties and any VAT. Yoyodyne Consulting will provide RoHS declarations with all orders.  The first articles have passed testing and production has been ordered. Custom aluminum encloses are being manufactured and should arrive in 7-10 day. Shipping of the assembled units is expected to start at the end of January 2019 or earlier.


The initial run of the UADC4 is priced at $495US. This is converted to Canadian dollars at the Bank of Canada official exchange rate of 1.36 which totals to 673.20 Canadian funds. The PayPal transaction fee of 3.9% is added to this total giving  a total price of $693.20 Canadian with shipping extra.

::Shipping costs::

Shipping is broken into 2 regions; USA and everyone else.  There are 2 shipping charges for both regions, without and with insurance.  Please choose the correct shipping: USA or Other. If you choose the wrong shipping, ie USA but live in the EU, I will be forced to refund your money and you will need to redo the purchase.

Payment is via PayPal and in Canadian dollars only. Payment in US dollars can only be done via bank wire transfer. Please contact me at for banking information.

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UADC4 User Manual

HB9DRI maintains the USDC4 user manual in his site downloads section.  Download the manual and become familar with its setup and usage.

UADC4 User Manual

UADC4 front panel showing power LED and USB connection

UADC4 real panel showing DC power, power switch, I/Q inputs as well as ground banana jack