Yes We Scan: The Advantages of Solid-State Radars

As Solid-State weather radars are slowly gaining ground in the traditional market, it might be useful for customers, who are yet to understand the full potential of this technology, to sum up their advantages. And to be fair, also explain how we deal with possible disadvantages.

What are Solid-State weather radars? In Solid-State radars, the signal is amplified using a Solid-State Power Amplifier (SSPA) compared to Magnetron or Klystron usage in traditional radars.

Solid-State Power Amplifiers use in general significantly less electricity, are much less expensive to purchase, are safer for operators, are less fragile so less prone to breakage, and are lighter and much more compact.

Simply put, mastering this technology opens completely new possibilities, making radars agile, significantly cheaper, and therefore available to a wider spectrum of customers.

Backpack radar

A long-lasting dream has come true. Meteopress is the only C-band radar on the market where the entire technology is incorporated into the pedestal of the radar eliminating thus the need to build dedicated radar rooms.

Meteopress has incorporated the entire radar chain including signal processing into the electrical box on the back of the antenna. Meteopress is the only C-band radar currently on the market, which does not require additional space for any technology such as racks, waveguide dehydration, etc. Therefore there is no space needed below the radome floor or on the ground nearby. The radar can thus be installed onto a rooftop of an existing building without the need for a technical room, or onto a lattice mast.

There is also no need for a high-speed data connection of the pedestal to any dedicated signal processing equipment; all the products are generated inside the radar and the finished files are uploaded via a standard internet connection.

Another major advantage is the minimum length of waveguides. Meteopress C-band radar has about 1 - 5 meters of waveguide in total in the radar. Usually, large C-band or S-band radars have up to 40-75 meters of the waveguide, which can cause signal loss of up to 3dB.

Having the technology on the back of the reflector also enables us to omit rotary joints, multi-channel slip rings, and other fragile and expensive technology. This limits the need for maintenance and spare parts.

Immortal radar

In Meteopress Solid-State radars there are no consumables. Magnetrons and Klystrons are expensive parts with a limited lifetime. Solid-State Power Amplifiers are immortal - they do not degrade over time, and they last for decades.

In traditional radars, there is a high need for regular maintenance. There was limited maintenance in Meteopress radar to start with, but there is an option now to change the gearing in the azimuthal motor for a direct drive motor and thus eliminating the last maintainable part. So you can now order a completely maintenance-free radar.

In the current situation in the energy markets and with regard to Global Climate Change, we are proud that Meteopress C-band radar is the most ecological radar on the market. It has by far the lowest power consumption on the market. Below is the comparison of the power consumption of different radar types:

Meteopress Solid-State C-band radar can save between 50 % - 95 % of the power consumption of conventional radar. Regular household electricity is enough to power the radar thus reducing the infrastructure costs necessary and operational costs.

With the power consumption of our entry-level 2.4m 1.7degree beam Solid State radar at 500W, it is possible to even build zero-infrastructure C-band radar in an off-grid version. The power is supplied by solar panels or wind turbines and energy is stored in batteries, making it the first zero-infrastructure radar on the market.

It's all about money

The radar is built in a completely new, innovative way so we could eliminate many of the traditional high costs. We do not purchase ready-made traditional parts, we manufacture our own where possible. We manufacture in-house signal processing, pedestals, radomes, and other parts. We use a lot of COTS components where possible.  

All that brings the price of Meteopress C-band radars to previously unseen levels. The acquisition price of C-band Solid-State radars matches the price market expected in X-band radar levels and is at about 50-70% of conventional magnetron C-band radars. But acquisition price is only one component of the Total Cost of Ownership in the radar project.

Infrastructure-light radar

As mentioned above, we have eliminated the need for expensive infrastructure with our current product. Radar power consumption is very low, so you can make do with a basic household electricity connection or even solar. This eliminates the need for high-voltage power lines, that traditional radars can require. This can add millions of dollars to the budget, as radars are usually built on high mountains with no electricity present.

Another pleasant characteristic of the Meteopress radar line is that it is one of the lightest in the market. By shedding weight, we can bring our 1degree beam C-band radar to below 750 kg of weight, which is below 1500 pounds. The 2.4m ECO super light version weighs below 500 kg. This allows both of these radars to be installed on conventional roofs or other lighter structures.

Instead of a heavy concrete tower with a dedicated radar room nearby, you can build a light lattice tower with approx. 20% of the budget, again saving significantly on the whole project. Meteopress also offers semi-permanent or mobile C-band solutions which utilize the advantage of low weight, compact design, and low power consumption.

Solid-State Signal processing advantages

Peak power equivalent

Thanks to the technological shift towards Solid-State, much less power is needed to achieve the same level of quality of received data. When comparing to classical magnetron radar with an output power of 250 kW, Solid-state radars usually exhibit about 50 times lower peak pulse power than their magnetron counterparts (e.g. Meteopress C-band has a 5kW transmitter output, compared to commonly used 250kW magnetron radars).

However, their pulse is 50 times longer than the pulse of magnetron radars (e.g. Meteopress C-band has a 100us long pulse, compared to the commonly used 2us pulse in magnetron radars), so the total transmitted energy is equivalent. The pulse is internally modulated by a pseudorandom sequence, so the range resolution is in the same relation to radio bandwidth as with magnetron radars.

This paper provides a detailed analysis of the pulse length/energy equation.

Is your cone half empty?

With the 100us pulse of a Solid-State radar, the pulse is 30 km "long", so it takes the first 15 km of the observed range to come back and forth. At distances below 15 km, only part (the end) of the pulse is received, and the sensitivity and range resolution suffers. The range problem is mitigated by using a shorter filling pulse, which has a shorter blind range because of its shortness (e.g. 10us = 1.5km), combining this with partial pulse recovery (e.g. approximately 1/3 of the resolution in 1/3 of the range = 500m) to obtain data even in the short pulse blind range.

The short pulse has lower energy (e.g. in this example, 100us long pulse compared to 10us short pulse = 1/10 of the energy) and thus lower absolute sensitivity, however, the targets in the short-range have much stronger echo as they are near. In meteorology, the targets fade with the second power of the distance, and the common range of the radars used is at least 100km. Therefore, a target at 10km has 100x stronger echo than a target at 100km and is thus easy to discern with 10x less energy.

Although Meteopress's precise solution is regarded as a company secret, we have used a combination of several techniques to solve it. In the attached image you can see a) a Meteopress C-band radar image without the blind range mitigation, b) a fully cleaned measured image with the blind range mitigation applied. Our coverage limit is now 600 meters from the radar.

Unlocking the impossible

Because of the low pulse repetition frequency (PRF) of most coherent pulsed radars, which maximizes the coverage in range, the amount of Doppler processing is limited. The Doppler processor can only process velocities up to ±1/2 the PRF of the radar, sampling restricts measurements to about 75 miles per hour.

Meteopress's innovative approach to radar technology allows for an Unlimited Doppler by measuring phase shift at the beginning vs. end of the pulse. We can obtain a coarse velocity estimate with Nyquist velocity exceeding 1000 km/hr, 623 mph, then compute the precise value using the standard Doppler way by measuring the phase shift of two consecutive pulses.

Another technique is implemented for second-trip echo suppression. The radar can transmit multiple pulses in a round-robin fashion; these pulses are designed in a way that cross-correlation between them is zero (for example, one can transmit an "up-chirp" and then a "down-chirp" in the next pulse). With this, the radar can run at the maximum 1000 Hz PRF the whole time, providing the maximum total transmitted energy, while covering the standard 300km range.

Scientific advantages

Software based radar

The design of Meteopress radars can be called Software based radar. The signals to be transmitted are generated in a conventional computer inside the radar and then transmitted by a Software Defined Radio through the radio chain.

This concept allows greater flexibility in signal generation and signal processing. You can run multiple signal processes simultaneously. One can be used for operational data generation, second and the other can be used for research, calibration, and/or other uses. The possibilities are limitless and the Meteopress team is here to help explore the full potential of this technology.

Here you are not bound by the hardware, which generates a signal that is unchangeable. Each transmitted pulse can be different from the previous one, making the experiments easy.

Radar also generates and stores I/Q data in an easily accessible format so you can re-run your experiments later and see the results immediately.

Noise channel

Interference is a challenge for meteorological radars, especially in the C-band, where various Wi-Fi and other data links operate. And even in bands where interference from man-made sources is rarely seen, one would still like to get monitoring of noise floor level, signal-to-noise ratio, and overall performance of the system. As Meteopress processes the wideband signal from the software-defined radio entirely in a standard computer, it was easy to split it into two channels: one that precisely matches the channel where the radar transmits, and one that covers the immediately adjacent frequencies. As the interference rarely perfectly aligns with the exact radar frequencies, we obtain an estimate of the noise level for each data sample by observing energy received in the noise channel.

This allows us to for example selectively remove individual Wi-Fi packets that contaminated the data, recover the data from in-between them, or identify and blank any new interference source immediately as it occurs.

Meteopress's innovation does not end only in the radars themselves, but also in the way radars are manufactured. We want to serve our customers quickly in the most efficient way possible. Our average delivery time is currently four months and we are keeping one radar in stock including Power Amplifiers, so we can ship the radar immediately.

This means that the guaranteed delivery time for most Meteopress radar models is now 6-9 months, with radars being shipped on average in 4 months.

The packing is arranged in two different ways - the compact model can be packed so it can be transported as air cargo, so you can have it delivered in 3-4 weeks. The second packing option is the economical one, where radar is packed into a standard shipping container for slower, but more economical transportation.

2-day installations

Once the radar reaches its destination, Meteopress's deployment team arrives and assists the customer's team with the installation. The radar is very modular, so we have been able to deploy the radar within two days. From assembly on the ground to radar rotation it takes less than five hours.

Quick installations also mean another significant saving on the deployment budget. Meaning less time is spent, which means lower costs are incurred.