Monty Python and the Search for the TAC-3290
December 11, 2020Kelsey Ryon
An uncommon likeness
Arguably, one of the greatest movies ever written was Monty Python and the Holy Grail. It was funny, budget-friendly—maybe to a comedic fault—and maintained the audience’s attention while the protagonist’s destinations continued to shift as he searched for the holy grail.
That impressive level of flexibility is important in many ways, and this is where the unlikely overlap between signal intelligence and electronic warfare solutions and an odd movie from the mid-70s occurs. As missions change, be it from one castle to another or one suspicious signal to another, agility in the field is critical. And just as this movie has survived generations and their evolving humor, sometimes really impressive signal intelligence solutions can do the same with their evolving counterparts.
A flexible architecture
With tuners, some applications require a wide IF bandwidth to effectively digitize a signal and others are a better fit for a narrower IF with better sensitivity. Historically, a fixed IF output of the downconverter simplified the system design and build, leading to a generally less expensive setup, but that fixed intermediate frequency (IF) comes with some limitations, such as restricted frequency planning. These limitations pioneered the drive for a new architecture design that could be something closer to a one-size-fits-all solution. Because varying microwave converters use different IF bands, matching them with downstream digitizers is a challenge. To resolve this, we’ve developed an agile IF architecture that maintains the necessary benefits of traditional systems while simultaneously providing the flexibility to dynamically adjust the IF band. This is a ready-for-anything kind of holy grail making adjustment of the IF band possible in the field, offering a flexible solution for users by optimizing mission-to-mission capabilities with easy integration with various digitizers.
About the agile IF holy grail
Mercury’s now acquirable holy grail is the TAC-3290. This is an ultra-wideband microwave tuner that brings an unprecedented level of flexibility and high-performance microwave frequency conversion to users in space-constrained environments. What was formerly only possible in a rackmount form factor can now be achieved with a product that could fit in a backpack, much like the one the coconut-clanking servant carried throughout the quest for the holy grail. The TAC-3290 offers ultra-low phase noise to better support SIGINT applications, single and dual coherent channels, and tuning up to 44 GHz with an extension. This allows for more effective analyzation and collection of a wider range of signals. Users can maximize digitizer results from signal records and downstream equipment with complete control over the output frequency and bandwidth making for an overall impressive piece of equipment.
Proven great without breaking out your largest scales
Comparing this to older tuner options, working with a fixed system seemed the more affordable option. However, that’s no longer the case with the TAC-3290. Mission-to-mission flexibility has the cost benefits of leading to a more sustainable overall system by extending the system lifespan. A single microwave converter can be used without sacrificing performance when, historically, multiple converters would be required. Having a multi-IBW solution reduces costs and helps minimize total system size. You could think of it like this: the way a single actor such as John Cleese has the talent to be the black knight, Sir Lancelot the Brave and the swallow-savvy guard, the TAC-3290 can be adapted for .5 GHz, 1 GHz or 2 GHz operation just as the director, or should we say operator, needs to match the signals of interest. Capturing and processing an adversary’s signal with this bandwidth and adaptability built into a single product is a groundbreaking achievement. This contributes to better control of the electromagnetic spectrum and a strategic advantage when it comes to upgrading system elements. Now, in regard to the weight of this compact tuner as it compares to a duck, I’ve requested that information from the engineers. But, unfortunately, I get the impression they’re ignoring my request on this matter and keep directing me to the specs listed on the datasheet.
Staying ahead of threats more serious than catapulted cows
The agile IF architecture for the TAC-3290 simplifies system updates. In an environment of rapidly emerging electronic threats, EW and ELINT systems must be regularly updated to incorporate the latest technology. Unfortunately, these updates are generally time consuming and costly. The TAC-3290’s agile IF architecture makes it possible to reuse the same microwave frequency tuner through multiple system upgrades, which extends the operational life of the tuner and significantly reduces the cost. Of the types of technology improvements that drive system updates, most of the changes are on the digital side, due to pace of processor and software technology driven by Moore’s Law (the idea that the number of transistors in a dense integrated circuit doubles about every two years). The TAC-3290 can support multiple upgrades and can operate with a new digitizer when the latest generation of ADCs and DACs have evolved. This is a leap forward from traditional systems, where updating the digitizer required changing the microwave converter.
The Knights who say Nyquist
The microwave tuner, like any, is dependent on the specific digitizer because the IF from the converter must be restricted to a single Nyquist zone. The digitizer’s Nyquist zones are defined by its data rate and the number of samples per frequency component. For example, if an ADC has a data rate of 2 GSPS, the first Nyquist zone extends from DC through 1 GHz, and the second Nyquist zone starts at 1 GHz and extends to 2 GHz. A signal spanning two Nyquist zones causes aliasing, i.e., signals from all the Nyquist zones are mapped into the first zone. To prevent this, anti-aliasing filters are used to limit the input frequency range; however, this requires the input signal to be constrained to a single Nyquist zone. With a fixed IF architecture, modifying the data rate of the digitizer results in a new frequency plan and requires a new microwave converter. But with an agile IF architecture, the frequency plan can be modified and the existing microwave converter will support multiple updates to the digitizer.
Seems like magic, but it’s not a witch
The TAC-3290 seemingly does the impossible. Instead of designing a new microwave transceiver, a costly and time intensive effort, the original transceiver can simply be programmed to a different IF band and IBW in the field and as needed. This ability to optimize the IF from mission to mission, as well as configure the converter to operate with a range of digitizers, enables a flexible and more future-proof approach to EW and ELINT system design. As new threats emerge, excluding those with big sharp teeth, this capability is critical to maintaining spectrum superiority in harsh environments.
For additional reading with fewer movie references, check out the Agile IF article diving into more of the details behind this product’s design. To learn more about the TAC-3290, visit our product page or read our press release. And if you haven’t already, I encourage you to tune into Netflix and watch Monty Python and the Holy Grail.